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stb-imv/stb_image.c
nothings.org d43cc68f50 initial checkin
2007-06-25 03:45:23 +00:00

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/* stbi-0.92 - public domain JPEG/PNG reader - http://nothings.org/stb_image.c
when you control the images you're loading
TODO:
stbi_info_*
history:
0.92 read 4,8,16,24,32-bit BMP files of several formats
0.91 output 24-bit Windows 3.0 BMP files
0.90 fix a few more warnings; bump version number to approach 1.0
0.61 bugfixes due to Marc LeBlanc, Christopher Lloyd
0.60 fix compiling as c++
0.59 fix warnings: merge Dave Moore's -Wall fixes
0.58 fix bug: zlib uncompressed mode len/nlen was wrong endian
0.57 fix bug: jpg last huffman symbol before marker was >9 bits but less
than 16 available
0.56 fix bug: zlib uncompressed mode len vs. nlen
0.55 fix bug: restart_interval not initialized to 0
0.54 allow NULL for 'int *comp'
0.53 fix bug in png 3->4; speedup png decoding
0.52 png handles req_comp=3,4 directly; minor cleanup; jpeg comments
0.51 obey req_comp requests, 1-component jpegs return as 1-component,
on 'test' only check type, not whether we support this variant
*/
//// begin header file ////////////////////////////////////////////////////
//
// Limitations:
// - no progressive/interlaced support (jpeg, png)
// - 8-bit samples only (jpeg, png)
// - not threadsafe
// - channel subsampling of at most 2 in each dimension (jpeg)
// - no delayed line count (jpeg) -- image height must be in header
// - unsophisticated error handling
//
// Basic usage:
// int x,y,n;
// unsigned char *data = stbi_load(filename, &x, &y, &n, 0);
// // ... process data if not NULL ...
// // ... x = width, y = height, n = # 8-bit components per pixel ...
// // ... replace '0' with '1'..'4' to force that many components per pixel
// stbi_image_free(data)
//
// Standard parameters:
// int *x -- outputs image width in pixels
// int *y -- outputs image height in pixels
// int *comp -- outputs # of image components in image file
// int req_comp -- if non-zero, # of image components requested in result
//
// The return value from an image loader is an 'unsigned char *' which points
// to the pixel data. The pixel data consists of *y scanlines of *x pixels,
// with each pixel consisting of N interleaved 8-bit components; the first
// pixel pointed to is top-left-most in the image. There is no padding between
// image scanlines or between pixels, regardless of format. The number of
// components N is 'req_comp' if req_comp is non-zero, or *comp otherwise.
// If req_comp is non-zero, *comp has the number of components that _would_
// have been output otherwise. E.g. if you set req_comp to 4, you will always
// get RGBA output, but you can check *comp to easily see if it's opaque.
//
// An output image with N components has the following components interleaved
// in this order in each pixel:
//
// N=#comp components
// 1 grey
// 2 grey, alpha
// 3 red, green, blue
// 4 red, green, blue, alpha
//
// If image loading fails for any reason, the return value will be NULL,
// and *x, *y, *comp will be unchanged. The function stbi_failure_reason()
// can be queried for an extremely brief, end-user unfriendly explanation
// of why the load failed. Define STB_IMAGE_NO_FAILURE_REASON to avoid
// compiling these strings at all.
//
// Paletted PNG images are automatically depalettized.
#include <stdio.h>
enum
{
STBI_default = 0, // only used for req_comp
STBI_grey = 1,
STBI_grey_alpha = 2,
STBI_rgb = 3,
STBI_rgb_alpha = 4,
};
typedef unsigned char stbi_uc;
#ifdef __cplusplus
extern "C" {
#endif
// WRITING API
#ifndef STBI_NO_WRITE
// write a BMP/TGA file given tightly packed 'comp' channels (no padding, nor bmp-stride-padding)
// (you must include the appropriate extension in the filename).
// returns TRUE on success, FALSE if couldn't open file, error writing file
extern int stbi_write_bmp (char *filename, int x, int y, int comp, void *data);
extern int stbi_write_tga (char *filename, int x, int y, int comp, void *data);
#endif
// PRIMARY API - works on images of any type
// load image by filename, open file, or memory buffer
extern stbi_uc *stbi_load (char *filename, int *x, int *y, int *comp, int req_comp);
extern stbi_uc *stbi_load_from_file (FILE *f, int *x, int *y, int *comp, int req_comp);
extern stbi_uc *stbi_load_from_memory(stbi_uc *buffer, int len, int *x, int *y, int *comp, int req_comp);
// for stbi_load_from_file, file pointer is left pointing immediately after image
// get a VERY brief reason for failure
extern char *stbi_failure_reason (void);
// free the loaded image -- this is just free()
extern void stbi_image_free (stbi_uc *retval_from_stbi_load);
// get image dimensions & components without fully decoding
extern int stbi_info (char *filename, int *x, int *y, int *comp);
extern int stbi_info_from_file (char *filename, int *x, int *y, int *comp);
extern int stbi_info_from_memory(stbi_uc *buffer, int len, int *x, int *y, int *comp);
// ZLIB client - used by PNG, available for other purposes
extern char *stbi_zlib_decode_malloc_guesssize(int initial_size, int *outlen);
extern char *stbi_zlib_decode_malloc(char *buffer, int len, int *outlen);
extern int stbi_zlib_decode_buffer(char *obuffer, int olen, char *ibuffer, int ilen);
// TYPE-SPECIFIC ACCESS
// is it a jpeg?
extern int stbi_jpeg_test_file (FILE *f);
extern int stbi_jpeg_test_memory (stbi_uc *buffer, int len);
extern stbi_uc *stbi_jpeg_load (char *filename, int *x, int *y, int *comp, int req_comp);
extern stbi_uc *stbi_jpeg_load_from_file (FILE *f, int *x, int *y, int *comp, int req_comp);
extern stbi_uc *stbi_jpeg_load_from_memory(stbi_uc *buffer, int len, int *x, int *y, int *comp, int req_comp);
extern int stbi_jpeg_info (char *filename, int *x, int *y, int *comp);
extern int stbi_jpeg_info_from_file (FILE *f, int *x, int *y, int *comp);
extern int stbi_jpeg_info_from_memory(stbi_uc *buffer, int len, int *x, int *y, int *comp);
extern int stbi_jpeg_dc_only; // only decode DC component
// is it a png?
extern int stbi_png_test_file (FILE *f);
extern int stbi_png_test_memory (stbi_uc *buffer, int len);
extern stbi_uc *stbi_png_load (char *filename, int *x, int *y, int *comp, int req_comp);
extern stbi_uc *stbi_png_load_from_file (FILE *f, int *x, int *y, int *comp, int req_comp);
extern stbi_uc *stbi_png_load_from_memory (stbi_uc *buffer, int len, int *x, int *y, int *comp, int req_comp);
extern int stbi_png_info (char *filename, int *x, int *y, int *comp);
extern int stbi_png_info_from_file (FILE *f, int *x, int *y, int *comp);
extern int stbi_png_info_from_memory (stbi_uc *buffer, int len, int *x, int *y, int *comp);
// is it a bmp?
extern int stbi_bmp_test_file (FILE *f);
extern int stbi_bmp_test_memory (stbi_uc *buffer, int len);
extern stbi_uc *stbi_bmp_load (char *filename, int *x, int *y, int *comp, int req_comp);
extern stbi_uc *stbi_bmp_load_from_file (FILE *f, int *x, int *y, int *comp, int req_comp);
extern stbi_uc *stbi_bmp_load_from_memory (stbi_uc *buffer, int len, int *x, int *y, int *comp, int req_comp);
#ifdef __cplusplus
}
#endif
//
//
//// end header file /////////////////////////////////////////////////////
#include <stdio.h>
#include <stdlib.h>
#include <memory.h>
#include <assert.h>
#include <stdarg.h>
#ifndef _MSC_VER
#define __forceinline
#endif
// implementation:
typedef unsigned char uint8;
typedef unsigned short uint16;
typedef signed short int16;
typedef unsigned int uint32;
typedef signed int int32;
typedef unsigned int uint;
// should produce compiler error if size is wrong
typedef unsigned char validate_uint32[sizeof(uint32)==4];
//////////////////////////////////////////////////////////////////////////////
//
// Generic API that works on all image types
//
static char *failure_reason;
char *stbi_failure_reason(void)
{
return failure_reason;
}
static int e(char *str)
{
failure_reason = str;
return 0;
}
#ifdef STB_IMAGE_NO_FAILURE_STRINGS
#define e(x) 0
#endif
#define ep(x) (e(x),NULL)
void stbi_image_free(unsigned char *retval_from_stbi_load)
{
free(retval_from_stbi_load);
}
unsigned char *stbi_load(char *filename, int *x, int *y, int *comp, int req_comp)
{
FILE *f = fopen(filename, "rb");
unsigned char *result;
if (!f) return ep("can't fopen");
result = stbi_load_from_file(f,x,y,comp,req_comp);
fclose(f);
return result;
}
unsigned char *stbi_load_from_file(FILE *f, int *x, int *y, int *comp, int req_comp)
{
if (stbi_jpeg_test_file(f))
return stbi_jpeg_load_from_file(f,x,y,comp,req_comp);
if (stbi_png_test_file(f))
return stbi_png_load_from_file(f,x,y,comp,req_comp);
if (stbi_bmp_test_file(f))
return stbi_bmp_load_from_file(f,x,y,comp,req_comp);
return ep("unknown image type");
}
unsigned char *stbi_load_from_memory(stbi_uc *buffer, int len, int *x, int *y, int *comp, int req_comp)
{
if (stbi_jpeg_test_memory(buffer,len))
return stbi_jpeg_load_from_memory(buffer,len,x,y,comp,req_comp);
if (stbi_png_test_memory(buffer,len))
return stbi_png_load_from_memory(buffer,len,x,y,comp,req_comp);
if (stbi_bmp_test_memory(buffer,len))
return stbi_bmp_load_from_memory(buffer,len,x,y,comp,req_comp);
return ep("unknown image type");
}
// @TODO: get image dimensions & components without fully decoding
extern int stbi_info (char *filename, int *x, int *y, int *comp);
extern int stbi_info_from_file (char *filename, int *x, int *y, int *comp);
extern int stbi_info_from_memory(stbi_uc *buffer, int len, int *x, int *y, int *comp);
//////////////////////////////////////////////////////////////////////////////
//
// Common code used by all image loaders
//
// image width, height, # components
static uint32 img_x, img_y;
static int img_n, img_out_n;
enum
{
SCAN_load=0,
SCAN_type,
SCAN_header,
};
// An API for reading either from memory or file.
// It fits on a single screen. No abstract base classes needed.
static FILE *img_file;
static uint8 *img_buffer, *img_buffer_end;
static void start_file(FILE *f)
{
img_file = f;
}
static void start_mem(uint8 *buffer, int len)
{
img_file = NULL;
img_buffer = buffer;
img_buffer_end = buffer+len;
}
static int get8(void)
{
if (img_file) {
int c = fgetc(img_file);
return c == EOF ? 0 : c;
} else {
if (img_buffer < img_buffer_end)
return *img_buffer++;
return 0;
}
}
static uint8 get8u(void)
{
return (uint8) get8();
}
static void skip(int n)
{
if (img_file)
fseek(img_file, n, SEEK_CUR);
else
img_buffer += n;
}
static int get16(void)
{
int z = get8();
return (z << 8) + get8();
}
static uint32 get32(void)
{
uint32 z = get16();
return (z << 16) + get16();
}
static int get16le(void)
{
int z = get8();
return z + (get8() << 8);
}
static uint32 get32le(void)
{
uint32 z = get16le();
return z + (get16le() << 16);
}
static void getn(stbi_uc *buffer, int n)
{
if (img_file)
fread(buffer, 1, n, img_file);
else {
memcpy(buffer, img_buffer, n);
img_buffer += n;
}
}
//////////////////////////////////////////////////////////////////////////////
//
// generic converter from built-in img_n to req_comp
// individual types do this automatically as much as possible (e.g. jpeg
// does all cases internally since it needs to colorspace convert anyway,
// and it never has alpha, so very few cases ). png can automatically
// interleave an alpha=255 channel, but falls back to this for other cases
//
// assume data buffer is malloced, so malloc a new one and free that one
// only failure mode is malloc failing
static uint8 compute_y(int r, int g, int b)
{
return (uint8) (((r*77) + (g*150) + (29*b)) >> 8);
}
static unsigned char *convert_format(unsigned char *data, int img_n, int req_comp)
{
uint i,j;
unsigned char *good;
if (req_comp == img_n) return data;
assert(req_comp >= 1 && req_comp <= 4);
good = (unsigned char *) malloc(req_comp * img_x * img_y);
if (good == NULL) {
free(data);
return ep("outofmem");
}
for (j=0; j < img_y; ++j) {
unsigned char *src = data + j * img_x * img_n ;
unsigned char *dest = good + j * img_x * req_comp;
#define COMBO(a,b) ((a)*8+(b))
#define CASE(a,b) case COMBO(a,b): for(i=0; i < img_x; ++i, src += a, dest += b)
// convert source image with img_n components to one with req_comp components
switch(COMBO(img_n, req_comp)) {
CASE(1,2) dest[0]=src[0], dest[1]=255; break;
CASE(1,3) dest[0]=dest[1]=dest[2]=src[0]; break;
CASE(1,4) dest[0]=dest[1]=dest[2]=src[0], dest[3]=255; break;
CASE(2,1) dest[0]=src[0]; break;
CASE(2,3) dest[0]=dest[1]=dest[2]=src[0]; break;
CASE(2,4) dest[0]=dest[1]=dest[2]=src[0], dest[3]=src[1]; break;
CASE(3,4) dest[0]=src[0],dest[1]=src[1],dest[2]=src[2],dest[3]=255; break;
CASE(3,1) dest[0]=compute_y(src[0],src[1],src[2]); break;
CASE(3,2) dest[0]=compute_y(src[0],src[1],src[2]), dest[1] = 255; break;
CASE(4,1) dest[0]=compute_y(src[0],src[1],src[2]); break;
CASE(4,2) dest[0]=compute_y(src[0],src[1],src[2]), dest[1] = src[3]; break;
CASE(4,3) dest[0]=src[0],dest[1]=src[1],dest[2]=src[2]; break;
default: assert(0);
}
#undef CASE
}
free(data);
img_out_n = req_comp;
return good;
}
//////////////////////////////////////////////////////////////////////////////
//
// "baseline" JPEG/JFIF decoder (not actually fully baseline implementation)
//
// simple implementation
// - channel subsampling of at most 2 in each dimension
// - doesn't support delayed output of y-dimension
// - simple interface (only one output format: 8-bit interleaved RGB)
// - doesn't try to recover corrupt jpegs
// - doesn't allow partial loading, loading multiple at once
// - still fast on x86 (copying globals into locals doesn't help x86)
// - allocates lots of intermediate memory (full size of all components)
// - non-interleaved case requires this anyway
// - allows good upsampling (see next)
// high-quality
// - upsampled channels are bilinearly interpolated, even across blocks
// - quality integer IDCT derived from IJG's 'slow'
// performance
// - fast huffman; reasonable integer IDCT
// - uses a lot of intermediate memory, could cache poorly
// - load http://nothings.org/remote/anemones.jpg 3 times on 2.8Ghz P4
// stb_jpeg: 1.34 seconds (MSVC6, default release build)
// stb_jpeg: 1.06 seconds (MSVC6, processor = Pentium Pro)
// IJL11.dll: 1.08 seconds (compiled by intel)
// IJG 1998: 0.98 seconds (MSVC6, makefile provided by IJG)
// IJG 1998: 0.95 seconds (MSVC6, makefile + proc=PPro)
int stbi_jpeg_dc_only;
// huffman decoding acceleration
#define FAST_BITS 9 // larger handles more cases; smaller stomps less cache
typedef struct
{
uint8 fast[1 << FAST_BITS];
// weirdly, repacking this into AoS is a 10% speed loss, instead of a win
uint16 code[256];
uint8 values[256];
uint8 size[257];
unsigned int maxcode[18];
int delta[17]; // old 'firstsymbol' - old 'firstcode'
} huffman;
static huffman huff_dc[4]; // baseline is 2 tables, extended is 4
static huffman huff_ac[4];
static uint8 dequant[4][64];
static int build_huffman(huffman *h, int *count)
{
int i,j,k=0,code;
// build size list for each symbol (from JPEG spec)
for (i=0; i < 16; ++i)
for (j=0; j < count[i]; ++j)
h->size[k++] = (uint8) (i+1);
h->size[k] = 0;
// compute actual symbols (from jpeg spec)
code = 0;
k = 0;
for(j=1; j <= 16; ++j) {
// compute delta to add to code to compute symbol id
h->delta[j] = k - code;
if (h->size[k] == j) {
while (h->size[k] == j)
h->code[k++] = (uint16) (code++);
if (code-1 >= (1 << j)) return e("bad code lengths");
}
// compute largest code + 1 for this size, preshifted as needed later
h->maxcode[j] = code << (16-j);
code <<= 1;
}
h->maxcode[j] = 0xffffffff;
// build non-spec acceleration table; 255 is flag for not-accelerated
memset(h->fast, 255, 1 << FAST_BITS);
for (i=0; i < k; ++i) {
int s = h->size[i];
if (s <= FAST_BITS) {
int c = h->code[i] << (FAST_BITS-s);
int m = 1 << (FAST_BITS-s);
for (j=0; j < m; ++j) {
h->fast[c+j] = (uint8) i;
}
}
}
return 1;
}
// sizes for components, interleaved MCUs
static int img_h_max, img_v_max;
static int img_mcu_x, img_mcu_y;
static int img_mcu_w, img_mcu_h;
// definition of jpeg image component
static struct
{
int id;
int h,v;
int tq;
int hd,ha;
int dc_pred;
int x,y,w2,h2;
uint8 *data;
} img_comp[4];
static unsigned long code_buffer; // jpeg entropy-coded buffer
static int code_bits; // number of valid bits
static unsigned char marker; // marker seen while filling entropy buffer
static int nomore; // flag if we saw a marker so must stop
static void grow_buffer_unsafe(void)
{
do {
int b = nomore ? 0 : get8();
if (b == 0xff) {
int c = get8();
if (c != 0) {
marker = (unsigned char) c;
nomore = 1;
return;
}
}
code_buffer = (code_buffer << 8) | b;
code_bits += 8;
} while (code_bits <= 24);
}
// (1 << n) - 1
static unsigned long bmask[17]={0,1,3,7,15,31,63,127,255,511,1023,2047,4095,8191,16383,32767,65535};
// decode a jpeg huffman value from the bitstream
__forceinline static int decode(huffman *h)
{
unsigned int temp;
int c,k;
if (code_bits < 16) grow_buffer_unsafe();
// look at the top FAST_BITS and determine what symbol ID it is,
// if the code is <= FAST_BITS
c = (code_buffer >> (code_bits - FAST_BITS)) & ((1 << FAST_BITS)-1);
k = h->fast[c];
if (k < 255) {
if (h->size[k] > code_bits)
return -1;
code_bits -= h->size[k];
return h->values[k];
}
// naive test is to shift the code_buffer down so k bits are
// valid, then test against maxcode. To speed this up, we've
// preshifted maxcode left so that it has (16-k) 0s at the
// end; in other words, regardless of the number of bits, it
// wants to be compared against something shifted to have 16;
// that way we don't need to shift inside the loop.
if (code_bits < 16)
temp = (code_buffer << (16 - code_bits)) & 0xffff;
else
temp = (code_buffer >> (code_bits - 16)) & 0xffff;
for (k=FAST_BITS+1 ; ; ++k)
if (temp < h->maxcode[k])
break;
if (k == 17) {
// error! code not found
code_bits -= 16;
return -1;
}
if (k > code_bits)
return -1;
// convert the huffman code to the symbol id
c = ((code_buffer >> (code_bits - k)) & bmask[k]) + h->delta[k];
assert((((code_buffer) >> (code_bits - h->size[c])) & bmask[h->size[c]]) == h->code[c]);
// convert the id to a symbol
code_bits -= k;
return h->values[c];
}
// combined JPEG 'receive' and JPEG 'extend', since baseline
// always extends everything it receives.
__forceinline static int extend_receive(int n)
{
unsigned int m = 1 << (n-1);
unsigned int k;
if (code_bits < n) grow_buffer_unsafe();
k = (code_buffer >> (code_bits - n)) & bmask[n];
code_bits -= n;
// the following test is probably a random branch that won't
// predict well. I tried to table accelerate it but failed.
// maybe it's compiling as a conditional move?
if (k < m)
return (-1 << n) + k + 1;
else
return k;
}
// given a value that's at position X in the zigzag stream,
// where does it appear in the 8x8 matrix coded as row-major?
static uint8 dezigzag[64+15] =
{
0, 1, 8, 16, 9, 2, 3, 10,
17, 24, 32, 25, 18, 11, 4, 5,
12, 19, 26, 33, 40, 48, 41, 34,
27, 20, 13, 6, 7, 14, 21, 28,
35, 42, 49, 56, 57, 50, 43, 36,
29, 22, 15, 23, 30, 37, 44, 51,
58, 59, 52, 45, 38, 31, 39, 46,
53, 60, 61, 54, 47, 55, 62, 63,
// let corrupt input sample past end
63, 63, 63, 63, 63, 63, 63, 63,
63, 63, 63, 63, 63, 63, 63
};
// decode one 64-entry block--
static int decode_block(short data[64], huffman *hdc, huffman *hac, int b)
{
int diff,dc,k;
int t = decode(hdc);
if (t < 0) return e("bad huffman code");
// 0 all the ac values now so we can do it 32-bits at a time
memset(data,0,64*sizeof(data[0]));
diff = t ? extend_receive(t) : 0;
dc = img_comp[b].dc_pred + diff;
img_comp[b].dc_pred = dc;
data[0] = (short) dc;
// decode AC components, see JPEG spec
k = 1;
do {
int r,s;
int rs = decode(hac);
if (rs < 0) return e("bad huffman code");
s = rs & 15;
r = rs >> 4;
if (s == 0) {
if (rs != 0xf0) break; // end block
k += 16;
} else {
k += r;
// decode into unzigzag'd location
data[dezigzag[k++]] = (short) extend_receive(s);
}
} while (k < 64);
return 1;
}
// take a -128..127 value and clamp it and convert to 0..255
__forceinline static uint8 clamp(int x)
{
x += 128;
// trick to use a single test to catch both cases
if ((unsigned int) x > 255) {
if (x < 0) return 0;
if (x > 255) return 255;
}
return (uint8) x;
}
#define f2f(x) (int) (((x) * 4096 + 0.5))
#define fsh(x) ((x) << 12)
// derived from jidctint -- DCT_ISLOW
#define IDCT_1D(s0,s1,s2,s3,s4,s5,s6,s7) \
int t0,t1,t2,t3,p1,p2,p3,p4,p5,x0,x1,x2,x3; \
p2 = s2; \
p3 = s6; \
p1 = (p2+p3) * f2f(0.5411961f); \
t2 = p1 + p3*f2f(-1.847759065f); \
t3 = p1 + p2*f2f( 0.765366865f); \
p2 = s0; \
p3 = s4; \
t0 = fsh(p2+p3); \
t1 = fsh(p2-p3); \
x0 = t0+t3; \
x3 = t0-t3; \
x1 = t1+t2; \
x2 = t1-t2; \
t0 = s7; \
t1 = s5; \
t2 = s3; \
t3 = s1; \
p3 = t0+t2; \
p4 = t1+t3; \
p1 = t0+t3; \
p2 = t1+t2; \
p5 = (p3+p4)*f2f( 1.175875602f); \
t0 = t0*f2f( 0.298631336f); \
t1 = t1*f2f( 2.053119869f); \
t2 = t2*f2f( 3.072711026f); \
t3 = t3*f2f( 1.501321110f); \
p1 = p5 + p1*f2f(-0.899976223f); \
p2 = p5 + p2*f2f(-2.562915447f); \
p3 = p3*f2f(-1.961570560f); \
p4 = p4*f2f(-0.390180644f); \
t3 += p1+p4; \
t2 += p2+p3; \
t1 += p2+p4; \
t0 += p1+p3;
// .344 seconds on 3*anemones.jpg
static void idct_block(uint8 *out, int out_stride, short data[64], uint8 *dequantize)
{
int i,val[64],*v=val;
uint8 *o,*dq = dequantize;
short *d = data;
if (stbi_jpeg_dc_only) {
// ok, I don't really know why this is right, but it seems to be:
int z = 128 + ((d[0] * dq[0]) >> 3);
for (i=0; i < 8; ++i) {
out[0] = out[1] = out[2] = out[3] = out[4] = out[5] = out[6] = out[7] = z;
out += out_stride;
}
return;
}
// columns
for (i=0; i < 8; ++i,++d,++dq, ++v) {
// if all zeroes, shortcut -- this avoids dequantizing 0s and IDCTing
if (d[ 8]==0 && d[16]==0 && d[24]==0 && d[32]==0
&& d[40]==0 && d[48]==0 && d[56]==0) {
// no shortcut 0 seconds
// (1|2|3|4|5|6|7)==0 0 seconds
// all separate -0.047 seconds
// 1 && 2|3 && 4|5 && 6|7: -0.047 seconds
int dcterm = d[0] * dq[0] << 2;
v[0] = v[8] = v[16] = v[24] = v[32] = v[40] = v[48] = v[56] = dcterm;
} else {
IDCT_1D(d[ 0]*dq[ 0],d[ 8]*dq[ 8],d[16]*dq[16],d[24]*dq[24],
d[32]*dq[32],d[40]*dq[40],d[48]*dq[48],d[56]*dq[56])
// constants scaled things up by 1<<12; let's bring them back
// down, but keep 2 extra bits of precision
x0 += 512; x1 += 512; x2 += 512; x3 += 512;
v[ 0] = (x0+t3) >> 10;
v[56] = (x0-t3) >> 10;
v[ 8] = (x1+t2) >> 10;
v[48] = (x1-t2) >> 10;
v[16] = (x2+t1) >> 10;
v[40] = (x2-t1) >> 10;
v[24] = (x3+t0) >> 10;
v[32] = (x3-t0) >> 10;
}
}
for (i=0, v=val, o=out; i < 8; ++i,v+=8,o+=out_stride) {
// no fast case since the first 1D IDCT spread components out
IDCT_1D(v[0],v[1],v[2],v[3],v[4],v[5],v[6],v[7])
// constants scaled things up by 1<<12, plus we had 1<<2 from first
// loop, plus horizontal and vertical each scale by sqrt(8) so together
// we've got an extra 1<<3, so 1<<17 total we need to remove.
x0 += 65536; x1 += 65536; x2 += 65536; x3 += 65536;
o[0] = clamp((x0+t3) >> 17);
o[7] = clamp((x0-t3) >> 17);
o[1] = clamp((x1+t2) >> 17);
o[6] = clamp((x1-t2) >> 17);
o[2] = clamp((x2+t1) >> 17);
o[5] = clamp((x2-t1) >> 17);
o[3] = clamp((x3+t0) >> 17);
o[4] = clamp((x3-t0) >> 17);
}
}
#define MARKER_none 0xff
// if there's a pending marker from the entropy stream, return that
// otherwise, fetch from the stream and get a marker. if there's no
// marker, return 0xff, which is never a valid marker value
static uint8 get_marker(void)
{
uint8 x;
if (marker != MARKER_none) { x = marker; marker = MARKER_none; return x; }
x = get8u();
if (x != 0xff) return MARKER_none;
while (x == 0xff)
x = get8u();
return x;
}
// in each scan, we'll have scan_n components, and the order
// of the components is specified by order[]
static int scan_n, order[4];
static int restart_interval, todo;
#define RESTART(x) ((x) >= 0xd0 && (x) <= 0xd7)
// after a restart interval, reset the entropy decoder and
// the dc prediction
static void reset(void)
{
code_bits = 0;
code_buffer = 0;
nomore = 0;
img_comp[0].dc_pred = img_comp[1].dc_pred = img_comp[2].dc_pred = 0;
marker = MARKER_none;
todo = restart_interval ? restart_interval : 0x7fffffff;
// no more than 1<<31 MCUs if no restart_interal? that's plenty safe,
// since we don't even allow 1<<30 pixels
}
static int parse_entropy_coded_data(void)
{
reset();
if (scan_n == 1) {
int i,j;
short data[64];
int n = order[0];
// non-interleaved data, we just need to process one block at a time,
// in trivial scanline order
// number of blocks to do just depends on how many actual "pixels" this
// component has, independent of interleaved MCU blocking and such
int w = (img_comp[n].x+7) >> 3;
int h = (img_comp[n].y+7) >> 3;
for (j=0; j < h; ++j) {
for (i=0; i < w; ++i) {
if (!decode_block(data, huff_dc+img_comp[n].hd, huff_ac+img_comp[n].ha, n)) return 0;
idct_block(img_comp[n].data+img_comp[n].w2*j*8+i*8, img_comp[n].w2, data, dequant[img_comp[n].tq]);
// every data block is an MCU, so countdown the restart interval
if (--todo <= 0) {
if (code_bits < 24) grow_buffer_unsafe();
// if it's NOT a restart, then just bail, so we get corrupt data
// rather than no data
if (!RESTART(marker)) return 1;
reset();
}
}
}
} else { // interleaved!
int i,j,k,x,y;
short data[64];
for (j=0; j < img_mcu_y; ++j) {
for (i=0; i < img_mcu_x; ++i) {
// scan an interleaved mcu... process scan_n components in order
for (k=0; k < scan_n; ++k) {
int n = order[k];
// scan out an mcu's worth of this component; that's just determined
// by the basic H and V specified for the component
for (y=0; y < img_comp[n].v; ++y) {
for (x=0; x < img_comp[n].h; ++x) {
int x2 = (i*img_comp[n].h + x)*8;
int y2 = (j*img_comp[n].v + y)*8;
if (!decode_block(data, huff_dc+img_comp[n].hd, huff_ac+img_comp[n].ha, n)) return 0;
idct_block(img_comp[n].data+img_comp[n].w2*y2+x2, img_comp[n].w2, data, dequant[img_comp[n].tq]);
}
}
}
// after all interleaved components, that's an interleaved MCU,
// so now count down the restart interval
if (--todo <= 0) {
if (code_bits < 24) grow_buffer_unsafe();
// if it's NOT a restart, then just bail, so we get corrupt data
// rather than no data
if (!RESTART(marker)) return 1;
reset();
}
}
}
}
return 1;
}
static int process_marker(int m)
{
int L;
switch (m) {
case MARKER_none: // no marker found
return e("expected marker");
case 0xC2: // SOF - progressive
return e("progressive jpeg");
case 0xDD: // DRI - specify restart interval
if (get16() != 4) return e("bad DRI len");
restart_interval = get16();
return 1;
case 0xDB: // DQT - define quantization table
L = get16()-2;
while (L > 0) {
int z = get8();
int p = z >> 4;
int t = z & 15,i;
if (p != 0) return e("bad DQT type");
if (t > 3) return e("bad DQT table");
for (i=0; i < 64; ++i)
dequant[t][dezigzag[i]] = get8u();
L -= 65;
}
return L==0;
case 0xC4: // DHT - define huffman table
L = get16()-2;
while (L > 0) {
uint8 *v;
int sizes[16],i,m=0;
int z = get8();
int tc = z >> 4;
int th = z & 15;
if (tc > 1 || th > 3) return e("bad DHT header");
for (i=0; i < 16; ++i) {
sizes[i] = get8();
m += sizes[i];
}
L -= 17;
if (tc == 0) {
if (!build_huffman(huff_dc+th, sizes)) return 0;
v = huff_dc[th].values;
} else {
if (!build_huffman(huff_ac+th, sizes)) return 0;
v = huff_ac[th].values;
}
for (i=0; i < m; ++i)
v[i] = get8u();
L -= m;
}
return L==0;
}
// check for comment block or APP blocks
if ((m >= 0xE0 && m <= 0xEF) || m == 0xFE) {
skip(get16()-2);
return 1;
}
return 0;
}
// after we see SOS
static int process_scan_header(void)
{
int i;
int Ls = get16();
scan_n = get8();
if (scan_n < 1 || scan_n > 4 || scan_n > (int) img_n) return e("bad SOS component count");
if (Ls != 6+2*scan_n) return e("bad SOS len");
for (i=0; i < scan_n; ++i) {
int id = get8(), which;
int z = get8();
for (which = 0; which < img_n; ++which)
if (img_comp[which].id == id)
break;
if (which == img_n) return 0;
img_comp[which].hd = z >> 4; if (img_comp[which].hd > 3) return e("bad DC huff");
img_comp[which].ha = z & 15; if (img_comp[which].ha > 3) return e("bad AC huff");
order[i] = which;
}
if (get8() != 0) return e("bad SOS");
get8(); // should be 63, but might be 0
if (get8() != 0) return e("bad SOS");
return 1;
}
static int process_frame_header(int scan)
{
int Lf,p,i,z, h_max=1,v_max=1;
Lf = get16(); if (Lf < 11) return e("bad SOF len"); // JPEG
p = get8(); if (p != 8) return e("only 8-bit"); // JPEG baseline
img_y = get16(); if (img_y == 0) return e("no header height"); // Legal, but we don't handle it!
img_x = get16(); if (img_x == 0) return e("0 width"); // JPEG requires
img_n = get8();
if (img_n != 3 && img_n != 1) return e("bad component count"); // JFIF requires
if (Lf != 8+3*img_n) return e("bad SOF len");
for (i=0; i < img_n; ++i) {
img_comp[i].id = get8();
if (img_comp[i].id != i+1) return e("bad component ID"); // JFIF requires
z = get8();
img_comp[i].h = (z >> 4); if (!img_comp[i].h || img_comp[i].h > 4) return e("bad H");
img_comp[i].v = z & 15; if (!img_comp[i].h || img_comp[i].h > 4) return e("bad V");
img_comp[i].tq = get8(); if (img_comp[i].tq > 3) return e("bad TQ");
}
if (scan != SCAN_load) return 1;
for (i=0; i < img_n; ++i) {
if (img_comp[i].h > h_max) h_max = img_comp[i].h;
if (img_comp[i].v > v_max) v_max = img_comp[i].v;
}
// compute interleaved mcu info
img_h_max = h_max;
img_v_max = v_max;
img_mcu_w = h_max * 8;
img_mcu_h = v_max * 8;
img_mcu_x = (img_x + img_mcu_w-1) / img_mcu_w;
img_mcu_y = (img_y + img_mcu_h-1) / img_mcu_h;
for (i=0; i < img_n; ++i) {
// number of effective pixels (e.g. for non-interleaved MCU)
img_comp[i].x = (img_x * img_comp[i].h + h_max-1) / h_max;
img_comp[i].y = (img_y * img_comp[i].v + v_max-1) / v_max;
// to simplify generation, we'll allocate enough memory to decode
// the bogus oversized data from using interleaved MCUs and their
// big blocks (e.g. a 16x16 iMCU on an image of width 33); we won't
// discard the extra data until colorspace conversion
img_comp[i].w2 = img_mcu_x * img_comp[i].h * 8;
img_comp[i].h2 = img_mcu_y * img_comp[i].v * 8;
img_comp[i].data = (uint8 *) malloc(img_comp[i].w2 * img_comp[i].h2);
}
return 1;
}
// use comparisons since in some cases we handle more than one case (e.g. SOF)
#define DNL(x) ((x) == 0xdc)
#define SOI(x) ((x) == 0xd8)
#define EOI(x) ((x) == 0xd9)
#define SOF(x) ((x) == 0xc0 || (x) == 0xc1)
#define SOS(x) ((x) == 0xda)
static int decode_jpeg_header(int scan)
{
int m;
marker = MARKER_none; // initialize cached marker to empty
m = get_marker();
if (!SOI(m)) return e("no SOI");
if (scan == SCAN_type) return 1;
m = get_marker();
while (!SOF(m)) {
if (!process_marker(m)) return 0;
m = get_marker();
}
if (!process_frame_header(scan)) return 0;
return 1;
}
static int decode_jpeg_image(void)
{
int m;
restart_interval = 0;
if (!decode_jpeg_header(SCAN_load)) return 0;
m = get_marker();
while (!EOI(m)) {
if (SOS(m)) {
if (!process_scan_header()) return 0;
if (!parse_entropy_coded_data()) return 0;
} else {
if (!process_marker(m)) return 0;
}
m = get_marker();
}
return 1;
}
// static jfif-centered resampling with cross-block smoothing
// here by cross-block smoothing what I mean is that the resampling
// is bilerp and crosses blocks; I dunno what IJG means
#define div4(x) ((uint8) ((x) >> 2))
static void resample_v_2(uint8 *out1, uint8 *input, int w, int h, int s)
{
// need to generate two samples vertically for every one in input
uint8 *above;
uint8 *below;
uint8 *source;
uint8 *out2;
int i,j;
source = input;
out2 = out1+w;
for (j=0; j < h; ++j) {
above = source;
source = input + j*s;
below = source + s; if (j == h-1) below = source;
for (i=0; i < w; ++i) {
int n = source[i]*3;
out1[i] = div4(above[i] + n);
out2[i] = div4(below[i] + n);
}
out1 += w*2;
out2 += w*2;
}
}
static void resample_h_2(uint8 *out, uint8 *input, int w, int h, int s)
{
// need to generate two samples horizontally for every one in input
int i,j;
if (w == 1) {
for (j=0; j < h; ++j)
out[j*2+0] = out[j*2+1] = input[j*s];
return;
}
for (j=0; j < h; ++j) {
out[0] = input[0];
out[1] = div4(input[0]*3 + input[1]);
for (i=1; i < w-1; ++i) {
int n = input[i]*3;
out[i*2-2] = div4(input[i-1] + n);
out[i*2-1] = div4(input[i+1] + n);
}
out[w*2-2] = div4(input[w-2]*3 + input[w-1]);
out[w*2-1] = input[w-1];
out += w*2;
input += s;
}
}
// .172 seconds on 3*anemones.jpg
static void resample_hv_2(uint8 *out, uint8 *input, int w, int h, int s)
{
// need to generate 2x2 samples for every one in input
int i,j;
int os = w*2;
// generate edge samples... @TODO lerp them!
for (i=0; i < w; ++i) {
out[i*2+0] = out[i*2+1] = input[i];
out[i*2+(2*h-1)*os+0] = out[i*2+(2*h-1)*os+1] = input[i+(h-1)*w];
}
for (j=0; j < h; ++j) {
out[j*os*2+0] = out[j*os*2+os+0] = input[j*w];
out[j*os*2+os-1] = out[j*os*2+os+os-1] = input[j*w+i-1];
}
// now generate interior samples; i & j point to top left of input
for (j=0; j < h-1; ++j) {
uint8 *in1 = input+j*s;
uint8 *in2 = in1 + s;
uint8 *out1 = out + (j*2+1)*os + 1;
uint8 *out2 = out1 + os;
for (i=0; i < w-1; ++i) {
int p00 = in1[0], p01=in1[1], p10=in2[0], p11=in2[1];
int p00_3 = p00*3, p01_3 = p01*3, p10_3 = p10*3, p11_3 = p11*3;
#define div16(x) ((uint8) ((x) >> 4))
out1[0] = div16(p00*9 + p01_3 + p10_3 + p11);
out1[1] = div16(p01*9 + p00_3 + p01_3 + p10);
out2[0] = div16(p10*9 + p11_3 + p00_3 + p01);
out2[1] = div16(p11*9 + p10_3 + p01_3 + p00);
out1 += 2;
out2 += 2;
++in1;
++in2;
}
}
}
#define float2fixed(x) ((int) ((x) * 65536 + 0.5))
// 0.38 seconds on 3*anemones.jpg (0.25 with processor = Pro)
// VC6 without processor=Pro is generating multiple LEAs per multiply!
static void YCbCr_to_RGB_row(uint8 *out, uint8 *y, uint8 *pcb, uint8 *pcr, int count, int step)
{
int i;
for (i=0; i < count; ++i) {
int y_fixed = (y[i] << 16) + 32768; // rounding
int r,g,b;
int cr = pcr[i] - 128;
int cb = pcb[i] - 128;
r = y_fixed + cr*float2fixed(1.40200f);
g = y_fixed - cr*float2fixed(0.71414f) - cb*float2fixed(0.34414f);
b = y_fixed + cb*float2fixed(1.77200f);
r >>= 16;
g >>= 16;
b >>= 16;
if ((unsigned) r > 255) { if (r < 0) r = 0; else r = 255; }
if ((unsigned) g > 255) { if (g < 0) g = 0; else g = 255; }
if ((unsigned) b > 255) { if (b < 0) b = 0; else b = 255; }
out[0] = (uint8)r;
out[1] = (uint8)g;
out[2] = (uint8)b;
if (step == 4) out[3] = 255;
out += step;
}
}
// clean up the temporary component buffers
static void cleanup_jpeg(void)
{
int i;
for (i=0; i < img_n; ++i) {
if (img_comp[i].data) {
free(img_comp[i].data);
img_comp[i].data = NULL;
}
}
}
static uint8 *load_jpeg_image(int *out_x, int *out_y, int *comp, int req_comp)
{
int i, n;
// validate req_comp
if (req_comp < 0 || req_comp > 4) return ep("bad req_comp");
// load a jpeg image from whichever source
if (!decode_jpeg_image()) { cleanup_jpeg(); return NULL; }
// determine actual number of components to generate
n = req_comp ? req_comp : img_n;
// resample components to full size... memory wasteful, but this
// lets us bilerp across blocks while upsampling
for (i=0; i < img_n; ++i) {
// if we're outputting fewer than 3 components, we're grey not RGB;
// in that case, don't bother upsampling Cb or Cr
if (n < 3 && i) continue;
// check if the component scale is less than max; if so it needs upsampling
if (img_comp[i].h != img_h_max || img_comp[i].v != img_v_max) {
int stride = img_x;
// allocate final size; make sure it's big enough for upsampling off
// the edges with upsample up to 4x4 (although we only support 2x2
// currently)
uint8 *new_data = (uint8 *) malloc((img_x+3)*(img_y+3));
if (img_comp[i].h*2 == img_h_max && img_comp[i].v*2 == img_v_max) {
int tx = (img_x+1)>>1;
resample_hv_2(new_data, img_comp[i].data, tx,(img_y+1)>>1, img_comp[i].w2);
stride = tx*2;
} else if (img_comp[i].h == img_h_max && img_comp[i].v*2 == img_v_max) {
resample_v_2(new_data, img_comp[i].data, img_x,(img_y+1)>>1, img_comp[i].w2);
} else if (img_comp[i].h*2 == img_h_max && img_comp[i].v == img_v_max) {
int tx = (img_x+1)>>1;
resample_h_2(new_data, img_comp[i].data, tx,img_y, img_comp[i].w2);
stride = tx*2;
} else {
// @TODO resample uncommon sampling pattern with nearest neighbor
free(new_data);
cleanup_jpeg();
return ep("uncommon H or V");
}
img_comp[i].w2 = stride;
free(img_comp[i].data);
img_comp[i].data = new_data;
}
}
// now convert components to output image
{
uint32 i,j;
uint8 *output = (uint8 *) malloc(n * img_x * img_y + 1);
if (n >= 3) { // output STBI_rgb_*
for (j=0; j < img_y; ++j) {
uint8 *y = img_comp[0].data + j*img_comp[0].w2;
uint8 *out = output + n * img_x * j;
if (img_n == 3) {
uint8 *cb = img_comp[1].data + j*img_comp[1].w2;
uint8 *cr = img_comp[2].data + j*img_comp[2].w2;
YCbCr_to_RGB_row(out, y, cb, cr, img_x, n);
} else {
for (i=0; i < img_x; ++i) {
out[0] = out[1] = out[2] = y[i];
out[3] = 255; // not used if n == 3
out += n;
}
}
}
} else { // output STBI_grey_*
for (j=0; j < img_y; ++j) {
uint8 *y = img_comp[0].data + j*img_comp[0].w2;
uint8 *out = output + n * img_x * j;
if (n == 1)
for (i=0; i < img_x; ++i) *out++ = *y++;
else
for (i=0; i < img_x; ++i) *out++ = *y++, *out++ = 255;
}
}
cleanup_jpeg();
*out_x = img_x;
*out_y = img_y;
if (comp) *comp = img_n; // report original components, not output
return output;
}
}
unsigned char *stbi_jpeg_load_from_file(FILE *f, int *x, int *y, int *comp, int req_comp)
{
start_file(f);
return load_jpeg_image(x,y,comp,req_comp);
}
unsigned char *stbi_jpeg_load(char *filename, int *x, int *y, int *comp, int req_comp)
{
unsigned char *data;
FILE *f = fopen(filename, "rb");
if (!f) return NULL;
data = stbi_jpeg_load_from_file(f,x,y,comp,req_comp);
fclose(f);
return data;
}
unsigned char *stbi_jpeg_load_from_memory(stbi_uc *buffer, int len, int *x, int *y, int *comp, int req_comp)
{
start_mem(buffer,len);
return load_jpeg_image(x,y,comp,req_comp);
}
int stbi_jpeg_test_file(FILE *f)
{
int n,r;
n = ftell(f);
start_file(f);
r = decode_jpeg_header(SCAN_type);
fseek(f,n,SEEK_SET);
return r;
}
int stbi_jpeg_test_memory(unsigned char *buffer, int len)
{
start_mem(buffer,len);
return decode_jpeg_header(SCAN_type);
}
// @TODO:
extern int stbi_jpeg_info (char *filename, int *x, int *y, int *comp);
extern int stbi_jpeg_info_from_file (FILE *f, int *x, int *y, int *comp);
extern int stbi_jpeg_info_from_memory(stbi_uc *buffer, int len, int *x, int *y, int *comp);
// public domain zlib decode v0.2 Sean Barrett 2006-11-18
// simple implementation
// - all input must be provided in an upfront buffer
// - all output is written to a single output buffer (can malloc/realloc)
// performance
// - fast huffman
// fast-way is faster to check than jpeg huffman, but slow way is slower
#define ZFAST_BITS 9 // accelerate all cases in default tables
#define ZFAST_MASK ((1 << ZFAST_BITS) - 1)
// zlib-style huffman encoding
// (jpegs packs from left, zlib from right, so can't share code)
typedef struct
{
uint16 fast[1 << ZFAST_BITS];
uint16 firstcode[16];
int maxcode[17];
uint16 firstsymbol[16];
uint8 size[288];
uint16 value[288];
} zhuffman;
__forceinline static int bitreverse16(int n)
{
n = ((n & 0xAAAA) >> 1) | ((n & 0x5555) << 1);
n = ((n & 0xCCCC) >> 2) | ((n & 0x3333) << 2);
n = ((n & 0xF0F0) >> 4) | ((n & 0x0F0F) << 4);
n = ((n & 0xFF00) >> 8) | ((n & 0x00FF) << 8);
return n;
}
__forceinline static int bit_reverse(int v, int bits)
{
assert(bits <= 16);
// to bit reverse n bits, reverse 16 and shift
// e.g. 11 bits, bit reverse and shift away 5
return bitreverse16(v) >> (16-bits);
}
static int zbuild_huffman(zhuffman *z, uint8 *sizelist, int num)
{
int i,k=0;
int code, next_code[16], sizes[17];
// DEFLATE spec for generating codes
memset(sizes, 0, sizeof(sizes));
memset(z->fast, 255, sizeof(z->fast));
for (i=0; i < num; ++i)
++sizes[sizelist[i]];
sizes[0] = 0;
for (i=1; i < 16; ++i)
assert(sizes[i] <= (1 << i));
code = 0;
for (i=1; i < 16; ++i) {
next_code[i] = code;
z->firstcode[i] = (uint16) code;
z->firstsymbol[i] = (uint16) k;
code = (code + sizes[i]);
if (sizes[i])
if (code-1 >= (1 << i)) return e("bad codelengths");
z->maxcode[i] = code << (16-i); // preshift for inner loop
code <<= 1;
k += sizes[i];
}
z->maxcode[16] = 0x10000; // sentinel
for (i=0; i < num; ++i) {
int s = sizelist[i];
if (s) {
int c = next_code[s] - z->firstcode[s] + z->firstsymbol[s];
z->size[c] = (uint8)s;
z->value[c] = (uint16)i;
if (s <= ZFAST_BITS) {
int k = bit_reverse(next_code[s],s);
while (k < (1 << ZFAST_BITS)) {
z->fast[k] = (uint16) c;
k += (1 << s);
}
}
++next_code[s];
}
}
return 1;
}
// zlib-from-memory implementation for PNG reading
// because PNG allows splitting the zlib stream arbitrarily,
// and it's annoying structurally to have PNG call ZLIB call PNG,
// we require PNG read all the IDATs and combine them into a single
// memory buffer
static uint8 *zbuffer, *zbuffer_end;
__forceinline static int zget8(void)
{
if (zbuffer >= zbuffer_end) return 0;
return *zbuffer++;
}
//static unsigned long code_buffer;
static int num_bits;
static void fill_bits(void)
{
do {
assert(code_buffer < (1U << num_bits));
code_buffer |= zget8() << num_bits;
num_bits += 8;
} while (num_bits <= 24);
}
__forceinline static unsigned int zreceive(int n)
{
unsigned int k;
if (num_bits < n) fill_bits();
k = code_buffer & ((1 << n) - 1);
code_buffer >>= n;
num_bits -= n;
return k;
}
__forceinline static int zhuffman_decode(zhuffman *z)
{
int b,s,k;
if (num_bits < 16) fill_bits();
b = z->fast[code_buffer & ZFAST_MASK];
if (b < 0xffff) {
s = z->size[b];
code_buffer >>= s;
num_bits -= s;
return z->value[b];
}
// not resolved by fast table, so compute it the slow way
// use jpeg approach, which requires MSbits at top
k = bit_reverse(code_buffer, 16);
for (s=ZFAST_BITS+1; ; ++s)
if (k < z->maxcode[s])
break;
if (s == 16) return -1; // invalid code!
// code size is s, so:
b = (k >> (16-s)) - z->firstcode[s] + z->firstsymbol[s];
assert(z->size[b] == s);
code_buffer >>= s;
num_bits -= s;
return z->value[b];
}
static char *zout;
static char *zout_start;
static char *zout_end;
static int z_expandable;
static int expand(int n) // need to make room for n bytes
{
char *q;
int cur, limit;
if (!z_expandable) return e("output buffer limit");
cur = (int) (zout - zout_start);
limit = (int) (zout_end - zout_start);
while (cur + n > limit)
limit *= 2;
q = (char *) realloc(zout_start, limit);
if (q == NULL) return e("outofmem");
zout_start = q;
zout = q + cur;
zout_end = q + limit;
return 1;
}
static zhuffman z_length, z_distance;
static int length_base[31] = {
3,4,5,6,7,8,9,10,11,13,
15,17,19,23,27,31,35,43,51,59,
67,83,99,115,131,163,195,227,258,0,0 };
static int length_extra[31]=
{ 0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,0,0,0 };
static int dist_base[32] = { 1,2,3,4,5,7,9,13,17,25,33,49,65,97,129,193,
257,385,513,769,1025,1537,2049,3073,4097,6145,8193,12289,16385,24577,0,0};
static int dist_extra[32] =
{ 0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13};
static int parse_huffman_block(void)
{
for(;;) {
int z = zhuffman_decode(&z_length);
if (z < 256) {
if (z < 0) return e("bad huffman code"); // error in huffman codes
if (zout >= zout_end) if (!expand(1)) return 0;
*zout++ = (char) z;
} else {
uint8 *p;
int len,dist;
if (z == 256) return 1;
z -= 257;
len = length_base[z];
if (length_extra[z]) len += zreceive(length_extra[z]);
z = zhuffman_decode(&z_distance);
if (z < 0) return e("bad huffman code");
dist = dist_base[z];
if (dist_extra[z]) dist += zreceive(dist_extra[z]);
if (zout - zout_start < dist) return e("bad dist");
if (zout + len > zout_end) if (!expand(len)) return 0;
p = (uint8 *) (zout - dist);
while (len--)
*zout++ = *p++;
}
}
}
static int compute_huffman_codes(void)
{
static uint8 length_dezigzag[19] = { 16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15 };
static zhuffman z_codelength; // static just to save stack space
uint8 lencodes[286+32+137];//padding for maximum single op
uint8 codelength_sizes[19];
int i,n;
int hlit = zreceive(5) + 257;
int hdist = zreceive(5) + 1;
int hclen = zreceive(4) + 4;
memset(codelength_sizes, 0, sizeof(codelength_sizes));
for (i=0; i < hclen; ++i) {
int s = zreceive(3);
codelength_sizes[length_dezigzag[i]] = (uint8) s;
}
if (!zbuild_huffman(&z_codelength, codelength_sizes, 19)) return 0;
n = 0;
while (n < hlit + hdist) {
int c = zhuffman_decode(&z_codelength);
assert(c >= 0 && c < 19);
if (c < 16)
lencodes[n++] = (uint8) c;
else if (c == 16) {
c = zreceive(2)+3;
memset(lencodes+n, lencodes[n-1], c);
n += c;
} else if (c == 17) {
c = zreceive(3)+3;
memset(lencodes+n, 0, c);
n += c;
} else {
assert(c == 18);
c = zreceive(7)+11;
memset(lencodes+n, 0, c);
n += c;
}
}
if (n != hlit+hdist) return e("bad codelengths");
if (!zbuild_huffman(&z_length, lencodes, hlit)) return 0;
if (!zbuild_huffman(&z_distance, lencodes+hlit, hdist)) return 0;
return 1;
}
static int parse_uncompressed_block(void)
{
uint8 header[4];
int len,nlen,k;
if (num_bits & 7)
zreceive(num_bits & 7); // discard
// drain the bit-packed data into header
k = 0;
while (num_bits > 0) {
header[k++] = (uint8) (code_buffer & 255); // wtf this warns?
code_buffer >>= 8;
num_bits -= 8;
}
assert(num_bits == 0);
// now fill header the normal way
while (k < 4)
header[k++] = (uint8) zget8();
len = header[1] * 256 + header[0];
nlen = header[3] * 256 + header[2];
if (nlen != (len ^ 0xffff)) return e("zlib corrupt");
if (zbuffer + len > zbuffer_end) return e("read past buffer");
if (zout + len > zout_end)
if (!expand(len)) return 0;
memcpy(zout, zbuffer, len);
zbuffer += len;
zout += len;
return 1;
}
static int parse_zlib_header(void)
{
int cmf = zget8();
int cm = cmf & 15;
/* int cinfo = cmf >> 4; */
int flg = zget8();
if ((cmf*256+flg) % 31 != 0) return e("bad zlib header"); // zlib spec
if (flg & 32) return e("no preset dict"); // preset dictionary not allowed in png
if (cm != 8) return e("bad compression"); // DEFLATE required for png
// window = 1 << (8 + cinfo)... but who cares, we fully buffer output
return 1;
}
static uint8 default_length[288], default_distance[32];
static void init_defaults(void)
{
int i; // use <= to match clearly with spec
for (i=0; i <= 143; ++i) default_length[i] = 8;
for ( ; i <= 255; ++i) default_length[i] = 9;
for ( ; i <= 279; ++i) default_length[i] = 7;
for ( ; i <= 287; ++i) default_length[i] = 8;
for (i=0; i <= 31; ++i) default_distance[i] = 5;
}
static int parse_zlib(void)
{
int final, type;
if (!parse_zlib_header()) return 0;
num_bits = 0;
code_buffer = 0;
do {
final = zreceive(1);
type = zreceive(2);
if (type == 0) {
if (!parse_uncompressed_block()) return 0;
} else if (type == 3) {
return 0;
} else {
if (type == 1) {
// use fixed code lengths
if (!default_length[0]) init_defaults();
if (!zbuild_huffman(&z_length , default_length , 288)) return 0;
if (!zbuild_huffman(&z_distance, default_distance, 32)) return 0;
} else {
if (!compute_huffman_codes()) return 0;
}
if (!parse_huffman_block()) return 0;
}
} while (!final);
return 1;
}
static int do_zlib(char *obuf, int olen, int exp)
{
zout_start = obuf;
zout = obuf;
zout_end = obuf + olen;
z_expandable = exp;
return parse_zlib();
}
char *stbi_zlib_decode_malloc_guesssize(int initial_size, int *outlen)
{
char *p = (char *) malloc(initial_size);
if (p == NULL) return NULL;
if (do_zlib(p, initial_size, 1)) {
*outlen = (int) (zout - zout_start);
return zout_start;
} else {
free(zout_start);
return NULL;
}
}
char *stbi_zlib_decode_malloc(char *buffer, int len, int *outlen)
{
zbuffer = (uint8 *) buffer;
zbuffer_end = (uint8 *) buffer+len;
return stbi_zlib_decode_malloc_guesssize(16384, outlen);
}
int stbi_zlib_decode_buffer(char *obuffer, int olen, char *ibuffer, int ilen)
{
zbuffer = (uint8 *) ibuffer;
zbuffer_end = (uint8 *) ibuffer + ilen;
if (do_zlib(obuffer, olen, 0))
return (int) (zout - zout_start);
else
return -1;
}
// public domain "baseline" PNG decoder v0.10 Sean Barrett 2006-11-18
// simple implementation
// - only 8-bit samples
// - no CRC checking
// - allocates lots of intermediate memory
// - avoids problem of streaming data between subsystems
// - avoids explicit window management
// performance
// - uses stb_zlib, a PD zlib implementation with fast huffman decoding
typedef struct
{
unsigned long length;
unsigned long type;
} chunk;
#define PNG_TYPE(a,b,c,d) (((a) << 24) + ((b) << 16) + ((c) << 8) + (d))
static chunk get_chunk_header(void)
{
chunk c;
c.length = get32();
c.type = get32();
return c;
}
static int check_png_header(void)
{
static uint8 png_sig[8] = { 137,80,78,71,13,10,26,10 };
int i;
for (i=0; i < 8; ++i)
if (get8() != png_sig[i]) return e("bad png sig");
return 1;
}
static uint8 *idata, *expanded, *out;
enum {
F_none=0, F_sub=1, F_up=2, F_avg=3, F_paeth=4,
F_avg_first, F_paeth_first,
};
static uint8 first_row_filter[5] =
{
F_none, F_sub, F_none, F_avg_first, F_paeth_first
};
static int paeth(int a, int b, int c)
{
int p = a + b - c;
int pa = abs(p-a);
int pb = abs(p-b);
int pc = abs(p-c);
if (pa <= pb && pa <= pc) return a;
if (pb <= pc) return b;
return c;
}
// create the png data from post-deflated data
static int create_png_image(uint8 *raw, uint32 raw_len, int out_n)
{
uint32 i,j,stride = img_x*out_n;
int k;
assert(out_n == img_n || out_n == img_n+1);
out = (uint8 *) malloc(img_x * img_y * out_n);
if (!out) return e("outofmem");
if (raw_len != (img_n * img_x + 1) * img_y) return e("not enough pixels");
for (j=0; j < img_y; ++j) {
uint8 *cur = out + stride*j;
uint8 *prior = cur - stride;
int filter = *raw++;
if (filter > 4) return e("invalid filter");
// if first row, use special filter that doesn't sample previous row
if (j == 0) filter = first_row_filter[filter];
// handle first pixel explicitly
for (k=0; k < img_n; ++k) {
switch(filter) {
case F_none : cur[k] = raw[k]; break;
case F_sub : cur[k] = raw[k]; break;
case F_up : cur[k] = raw[k] + prior[k]; break;
case F_avg : cur[k] = raw[k] + (prior[k]>>1); break;
case F_paeth : cur[k] = (uint8) (raw[k] + paeth(0,prior[k],0)); break;
case F_avg_first : cur[k] = raw[k]; break;
case F_paeth_first: cur[k] = raw[k]; break;
}
}
if (img_n != out_n) cur[img_n] = 255;
raw += img_n;
cur += out_n;
prior += out_n;
// this is a little gross, so that we don't switch per-pixel or per-component
if (img_n == out_n) {
#define CASE(f) \
case f: \
for (i=1; i < img_x; ++i, raw+=img_n,cur+=img_n,prior+=img_n) \
for (k=0; k < img_n; ++k)
switch(filter) {
CASE(F_none) cur[k] = raw[k]; break;
CASE(F_sub) cur[k] = raw[k] + cur[k-img_n]; break;
CASE(F_up) cur[k] = raw[k] + prior[k]; break;
CASE(F_avg) cur[k] = raw[k] + ((prior[k] + cur[k-img_n])>>1); break;
CASE(F_paeth) cur[k] = (uint8) (raw[k] + paeth(cur[k-img_n],prior[k],prior[k-img_n])); break;
CASE(F_avg_first) cur[k] = raw[k] + (cur[k-img_n] >> 1); break;
CASE(F_paeth_first) cur[k] = (uint8) (raw[k] + paeth(cur[k-img_n],0,0)); break;
}
#undef CASE
} else {
assert(img_n+1 == out_n);
#define CASE(f) \
case f: \
for (i=1; i < img_x; ++i, cur[img_n]=255,raw+=img_n,cur+=out_n,prior+=out_n) \
for (k=0; k < img_n; ++k)
switch(filter) {
CASE(F_none) cur[k] = raw[k]; break;
CASE(F_sub) cur[k] = raw[k] + cur[k-out_n]; break;
CASE(F_up) cur[k] = raw[k] + prior[k]; break;
CASE(F_avg) cur[k] = raw[k] + ((prior[k] + cur[k-out_n])>>1); break;
CASE(F_paeth) cur[k] = (uint8) (raw[k] + paeth(cur[k-out_n],prior[k],prior[k-out_n])); break;
CASE(F_avg_first) cur[k] = raw[k] + (cur[k-out_n] >> 1); break;
CASE(F_paeth_first) cur[k] = (uint8) (raw[k] + paeth(cur[k-out_n],0,0)); break;
}
#undef CASE
}
}
return 1;
}
static int compute_transparency(uint8 tc[3], int out_n)
{
uint32 i, pixel_count = img_x * img_y;
uint8 *p = out;
// compute color-based transparency, assuming we've
// already got 255 as the alpha value in the output
assert(out_n == 2 || out_n == 4);
p = out;
if (out_n == 2) {
for (i=0; i < pixel_count; ++i) {
p[1] = (p[0] == tc[0] ? 0 : 255);
p += 2;
}
} else {
for (i=0; i < pixel_count; ++i) {
if (p[0] == tc[0] && p[1] == tc[1] && p[2] == tc[2])
p[3] = 0;
p += 4;
}
}
return 1;
}
static int expand_palette(uint8 *palette, int len, int pal_img_n)
{
uint32 i, pixel_count = img_x * img_y;
uint8 *p, *temp_out, *orig = out;
p = (uint8 *) malloc(pixel_count * pal_img_n);
if (p == NULL) return e("outofmem");
// between here and free(out) below, exitting would leak
temp_out = p;
if (pal_img_n == 3) {
for (i=0; i < pixel_count; ++i) {
int n = orig[i]*4;
p[0] = palette[n ];
p[1] = palette[n+1];
p[2] = palette[n+2];
p += 3;
}
} else {
for (i=0; i < pixel_count; ++i) {
int n = orig[i]*4;
p[0] = palette[n ];
p[1] = palette[n+1];
p[2] = palette[n+2];
p[3] = palette[n+3];
p += 4;
}
}
free(out);
out = temp_out;
return 1;
}
static int parse_png_file(int scan, int req_comp)
{
uint8 palette[1024], pal_img_n=0;
uint8 has_trans=0, tc[3];
uint32 ioff=0, idata_limit=0, i, pal_len=0;
int first=1,k;
if (!check_png_header()) return e("not png");
if (scan == SCAN_type) return 1;
for(;;first=0) {
chunk c = get_chunk_header();
if (first && c.type != PNG_TYPE('I','H','D','R'))
return e("first not IHDR");
switch (c.type) {
case PNG_TYPE('I','H','D','R'): {
int depth,color,interlace,comp,filter;
if (!first) return e("multiple IHDR");
if (c.length != 13) return e("bad IHDR len");
img_x = get32(); if (img_x > (1 << 24)) return e("too large");
img_y = get32(); if (img_y > (1 << 24)) return e("too large");
depth = get8(); if (depth != 8) return e("8bit only");
color = get8(); if (color > 6) return e("bad ctype");
if (color == 3) pal_img_n = 3; else if (color & 1) return e("bad ctype");
comp = get8(); if (comp) return e("bad comp method");
filter= get8(); if (filter) return e("bad filter method");
interlace = get8(); if (interlace) return e("interlaced");
if (!img_x || !img_y) return e("0-pixel image");
if (!pal_img_n) {
img_n = (color & 2 ? 3 : 1) + (color & 4 ? 1 : 0);
if ((1 << 30) / img_x / img_n < img_y) return e("too large");
if (scan == SCAN_header) return 1;
} else {
// if paletted, then pal_n is our final components, and
// img_n is # components to decompress/filter.
img_n = 1;
if ((1 << 30) / img_x / 4 < img_y) return e("too large");
// if SCAN_header, have to scan to see if we have a tRNS
}
break;
}
case PNG_TYPE('P','L','T','E'): {
if (c.length > 256*3) return e("invalid PLTE");
pal_len = c.length / 3;
if (pal_len * 3 != c.length) return e("invalid PLTE");
for (i=0; i < pal_len; ++i) {
palette[i*4+0] = get8u();
palette[i*4+1] = get8u();
palette[i*4+2] = get8u();
palette[i*4+3] = 255;
}
break;
}
case PNG_TYPE('t','R','N','S'): {
if (idata) return e("tRNS after IDAT");
if (pal_img_n) {
if (scan == SCAN_header) { img_n = 4; return 1; }
if (pal_len == 0) return e("tRNS before PLTE");
if (c.length > pal_len) return e("bad tRNS len");
for (i=0; i < c.length; ++i)
palette[i*4+3] = get8u();
} else {
if (!(img_n & 1)) return e("tRNS with alpha");
if (c.length != (uint32) img_n*2) return e("bad tRNS len");
has_trans = 1;
for (k=0; k < img_n; ++k)
tc[k] = (uint8) get16(); // non 8-bit images will be larger
}
break;
}
case PNG_TYPE('I','D','A','T'): {
if (pal_img_n && !pal_len) return e("no PLTE");
if (scan == SCAN_header) { img_n = pal_img_n; return 1; }
if (ioff + c.length > idata_limit) {
uint8 *p;
if (idata_limit == 0) idata_limit = c.length > 4096 ? c.length : 4096;
while (ioff + c.length > idata_limit)
idata_limit *= 2;
p = (uint8 *) realloc(idata, idata_limit); if (p == NULL) return e("outofmem");
idata = p;
}
if (img_file) {
if (fread(idata+ioff,1,c.length,img_file) != c.length) return e("outofdata");
} else {
memcpy(idata+ioff, img_buffer, c.length);
img_buffer += c.length;
}
ioff += c.length;
break;
}
case PNG_TYPE('I','E','N','D'): {
uint32 raw_len;
if (scan != SCAN_load) return 1;
if (idata == NULL) return e("no IDAT");
expanded = (uint8 *) stbi_zlib_decode_malloc((char *) idata, ioff, (int *) &raw_len);
if (expanded == NULL) return 0; // zlib should set error
free(idata); idata = NULL;
if ((req_comp == img_n+1 && req_comp != 3 && !pal_img_n) || has_trans)
img_out_n = img_n+1;
else
img_out_n = img_n;
if (!create_png_image(expanded, raw_len, img_out_n)) return 0;
if (has_trans)
if (!compute_transparency(tc, img_out_n)) return 0;
if (pal_img_n) {
// pal_img_n == 3 or 4
img_n = pal_img_n; // record the actual colors we had
img_out_n = pal_img_n;
if (req_comp >= 3) img_out_n = req_comp;
if (!expand_palette(palette, pal_len, img_out_n))
return 0;
}
free(expanded); expanded = NULL;
return 1;
}
default:
// if critical, fail
if ((c.type & (1 << 29)) == 0) {
#ifndef STB_IMAGE_NO_FAILURE_STRINGS
static char invalid_chunk[] = "XXXX chunk not known";
invalid_chunk[0] = (uint8) (c.type >> 24);
invalid_chunk[1] = (uint8) (c.type >> 16);
invalid_chunk[2] = (uint8) (c.type >> 8);
invalid_chunk[3] = (uint8) (c.type >> 0);
#endif
return e(invalid_chunk);
}
skip(c.length);
break;
}
// end of chunk, read and skip CRC
get8(); get8(); get8(); get8();
}
}
static unsigned char *do_png(int *x, int *y, int *n, int req_comp)
{
unsigned char *result=NULL;
if (req_comp < 0 || req_comp > 4) return ep("bad req_comp");
if (parse_png_file(SCAN_load, req_comp)) {
result = out;
out = NULL;
if (req_comp && req_comp != img_out_n) {
result = convert_format(result, img_out_n, req_comp);
if (result == NULL) return result;
}
*x = img_x;
*y = img_y;
if (n) *n = img_n;
}
free(out); out = NULL;
free(expanded); expanded = NULL;
free(idata); idata = NULL;
return result;
}
unsigned char *stbi_png_load_from_file(FILE *f, int *x, int *y, int *comp, int req_comp)
{
start_file(f);
return do_png(x,y,comp,req_comp);
}
unsigned char *stbi_png_load(char *filename, int *x, int *y, int *comp, int req_comp)
{
unsigned char *data;
FILE *f = fopen(filename, "rb");
if (!f) return NULL;
data = stbi_png_load_from_file(f,x,y,comp,req_comp);
fclose(f);
return data;
}
unsigned char *stbi_png_load_from_memory(unsigned char *buffer, int len, int *x, int *y, int *comp, int req_comp)
{
start_mem(buffer,len);
return do_png(x,y,comp,req_comp);
}
int stbi_png_test_file(FILE *f)
{
int n,r;
n = ftell(f);
start_file(f);
r = parse_png_file(SCAN_type,STBI_default);
fseek(f,n,SEEK_SET);
return r;
}
int stbi_png_test_memory(unsigned char *buffer, int len)
{
start_mem(buffer, len);
return parse_png_file(SCAN_type,STBI_default);
}
// TODO: load header from png
extern int stbi_png_info (char *filename, int *x, int *y, int *comp);
extern int stbi_png_info_from_file (FILE *f, int *x, int *y, int *comp);
extern int stbi_png_info_from_memory (stbi_uc *buffer, int len, int *x, int *y, int *comp);
/////////////////////// write image ///////////////////////
// Microsoft/Windows BMP image
static int bmp_test(void)
{
int sz;
if (get8() != 'B') return 0;
if (get8() != 'M') return 0;
get32le(); // discard filesize
get16le(); // discard reserved
get16le(); // discard reserved
get32le(); // discard data offset
sz = get32le();
if (sz == 12 || sz == 40 || sz == 108) return 1;
return 0;
}
int stbi_bmp_test_file (FILE *f)
{
int r,n = ftell(f);
start_file(f);
r = bmp_test();
fseek(f,n,SEEK_SET);
return r;
}
int stbi_bmp_test_memory (stbi_uc *buffer, int len)
{
start_mem(buffer, len);
return bmp_test();
}
// returns 0..31 for the highest set bit
static int high_bit(unsigned int z)
{
int n=0;
if (z == 0) return -1;
if (z >= 0x10000) n += 16, z >>= 16;
if (z >= 0x00100) n += 8, z >>= 8;
if (z >= 0x00010) n += 4, z >>= 4;
if (z >= 0x00004) n += 2, z >>= 2;
if (z >= 0x00002) n += 1, z >>= 1;
return n;
}
static int bitcount(unsigned int a)
{
a = (a & 0x55555555) + ((a >> 1) & 0x55555555); // max 2
a = (a & 0x33333333) + ((a >> 2) & 0x33333333); // max 4
a = (a + (a >> 4)) & 0x0f0f0f0f; // max 8 per 4, now 8 bits
a = (a + (a >> 8)); // max 16 per 8 bits
a = (a + (a >> 16)); // max 32 per 8 bits
return a & 0xff;
}
static int shiftsigned(int v, int shift, int bits)
{
int result;
int z=0;
if (shift < 0) v <<= -shift;
else v >>= shift;
result = v;
z = bits;
while (z < 8) {
result += v >> z;
z += bits;
}
return result;
}
static stbi_uc *bmp_load(int *x, int *y, int *comp, int req_comp)
{
unsigned int mr=0,mg=0,mb=0,ma=0;
stbi_uc pal[256][4];
int psize=0,i,j,compress=0,width;
int bpp, flip_vertically, pad, target, offset, hsz;
if (get8() != 'B' || get8() != 'M') return ep("not BMP");
get32le(); // discard filesize
get16le(); // discard reserved
get16le(); // discard reserved
offset = get32le();
hsz = get32le();
if (hsz != 12 && hsz != 40 && hsz != 108) return ep("unknown BMP");
failure_reason = "bad BMP";
img_x = get32le();
img_y = get32le();
if (get16le() != 1) return 0;
bpp = get16le();
if (bpp == 1) return ep("monochrome");
flip_vertically = img_y > 0;
img_y = abs(img_y);
if (hsz == 12) {
if (bpp < 24)
psize = (offset - 14 - 24) / 3;
} else {
compress = get32();
if (compress == 1 || compress == 2) return ep("BMP RLE");
get32le(); // discard sizeof
get32le(); // discard hres
get32le(); // discard vres
get32le(); // discard colorsused
get32le(); // discard max important
if (hsz == 40) {
if (bpp == 16 || bpp == 32) {
if (compress == 0) {
if (bpp == 32) {
mr = 0xff << 16;
mg = 0xff << 8;
mb = 0xff << 0;
} else {
mr = 31 << 10;
mg = 31 << 5;
mb = 31 << 0;
}
} else if (compress == 3) {
mr = get32le();
mg = get32le();
mb = get32le();
} else
return NULL;
}
} else {
assert(hsz == 108);
mr = get32le();
mg = get32le();
mb = get32le();
ma = get32le();
get32le(); // discard color space
for (i=0; i < 12; ++i)
get32le(); // discard color space parameters
}
if (bpp < 16)
psize = (offset - 14 - hsz) >> 2;
}
img_n = ma ? 4 : 3;
if (req_comp && req_comp >= 3) // we can directly decode 3 or 4
target = req_comp;
else
target = img_n; // if they want monochrome, we'll post-convert
out = (stbi_uc *) malloc(target * img_x * img_y);
if (!out) return ep("outofmem");
if (bpp < 16) {
int z=0;
if (psize == 0 || psize > 256) return ep("invalid");
for (i=0; i < psize; ++i) {
pal[i][2] = get8();
pal[i][1] = get8();
pal[i][0] = get8();
if (hsz != 12) get8();
pal[i][3] = 255;
}
skip(offset - 14 - hsz - psize * (hsz == 12 ? 3 : 4));
if (bpp == 4) width = (img_x + 1) >> 1;
else if (bpp == 8) width = img_x;
else return ep("bad bpp");
pad = (-width)&3;
for (j=0; j < (int) img_y; ++j) {
for (i=0; i < (int) img_x; i += 2) {
int v=get8(),v2;
if (bpp == 4) {
v2 = v & 15;
v >>= 4;
}
out[z++] = pal[v][0];
out[z++] = pal[v][1];
out[z++] = pal[v][2];
if (target == 4) out[z++] = 255;
if (i+1 == (int) img_x) break;
v = (bpp == 8) ? get8() : v2;
out[z++] = pal[v][0];
out[z++] = pal[v][1];
out[z++] = pal[v][2];
if (target == 4) out[z++] = 255;
}
skip(pad);
}
} else {
int rshift,gshift,bshift,ashift,rcount,gcount,bcount,acount;
int z = 0;
int easy=0;
skip(offset - 14 - hsz);
if (bpp == 24) width = 3 * img_x;
else if (bpp == 16) width = 2*img_x;
else /* bpp = 32 and pad = 0 */ width=0;
pad = (-width) & 3;
if (bpp == 24) {
easy = 1;
} else if (bpp == 32) {
if (mb == 0xff && mg == 0xff00 && mr == 0xff000000 && ma == 0xff000000)
easy = 2;
}
if (!easy) {
if (!mr || !mg || !mb) return ep("bad masks");
// right shift amt to put high bit in position #7
rshift = high_bit(mr)-7; rcount = bitcount(mr);
gshift = high_bit(mg)-7; gcount = bitcount(mr);
bshift = high_bit(mb)-7; bcount = bitcount(mr);
ashift = high_bit(ma)-7; acount = bitcount(mr);
}
for (j=0; j < (int) img_y; ++j) {
if (easy) {
for (i=0; i < (int) img_x; ++i) {
int a;
out[z+2] = get8();
out[z+1] = get8();
out[z+0] = get8();
z += 3;
a = (easy == 2 ? get8() : 255);
if (target == 4) out[z++] = a;
}
} else {
for (i=0; i < (int) img_x; ++i) {
unsigned long v = (bpp == 16 ? get16le() : get32le());
int a;
out[z++] = shiftsigned(v & mr, rshift, rcount);
out[z++] = shiftsigned(v & mg, gshift, gcount);
out[z++] = shiftsigned(v & mb, bshift, bcount);
a = (ma ? shiftsigned(v & ma, ashift, acount) : 255);
if (target == 4) out[z++] = a;
}
}
skip(pad);
}
}
if (flip_vertically) {
stbi_uc t;
for (j=0; j < (int) img_y>>1; ++j) {
stbi_uc *p1 = out + j *img_x*target;
stbi_uc *p2 = out + (img_y-1-j)*img_x*target;
for (i=0; i < (int) img_x*target; ++i) {
t = p1[i], p1[i] = p2[i], p2[i] = t;
}
}
}
if (req_comp && req_comp != target) {
out = convert_format(out, target, req_comp);
if (out == NULL) return out; // convert_format frees input on failure
}
*x = img_x;
*y = img_y;
if (comp) *comp = target;
return out;
}
stbi_uc *stbi_bmp_load (char *filename, int *x, int *y, int *comp, int req_comp)
{
stbi_uc *data;
FILE *f = fopen(filename, "rb");
if (!f) return NULL;
data = bmp_load(x,y,comp,req_comp);
fclose(f);
return data;
}
stbi_uc *stbi_bmp_load_from_file (FILE *f, int *x, int *y, int *comp, int req_comp)
{
start_file(f);
return bmp_load(x,y,comp,req_comp);
}
stbi_uc *stbi_bmp_load_from_memory (stbi_uc *buffer, int len, int *x, int *y, int *comp, int req_comp)
{
start_mem(buffer, len);
return bmp_load(x,y,comp,req_comp);
}
/////////////////////// write image ///////////////////////
#ifndef STBI_NO_WRITE
static void write8(FILE *f, int x) { uint8 z = (uint8) x; fwrite(&z,1,1,f); }
static void writefv(FILE *f, char *fmt, va_list v)
{
while (*fmt) {
switch (*fmt++) {
case ' ': break;
case '1': { uint8 x = va_arg(v, int); write8(f,x); break; }
case '2': { int16 x = va_arg(v, int); write8(f,x); write8(f,x>>8); break; }
case '4': { int32 x = va_arg(v, int); write8(f,x); write8(f,x>>8); write8(f,x>>16); write8(f,x>>24); break; }
default:
assert(0);
va_end(v);
return;
}
}
}
static void writef(FILE *f, char *fmt, ...)
{
va_list v;
va_start(v, fmt);
writefv(f,fmt,v);
va_end(v);
}
static void write_pixels(FILE *f, int rgb_dir, int vdir, int x, int y, int comp, void *data, int write_alpha, int scanline_pad)
{
uint8 bg[3] = { 255, 0, 255}, px[3];
uint32 zero = 0;
int i,j,k, j_end;
if (vdir < 0)
j_end = -1, j = y-1;
else
j_end = y, j = 0;
for (; j != j_end; j += vdir) {
for (i=0; i < x; ++i) {
uint8 *d = (uint8 *) data + (j*x+i)*comp;
if (write_alpha < 0)
fwrite(&d[comp-1], 1, 1, f);
switch (comp) {
case 1:
case 2: writef(f, "111", d[0],d[0],d[0]);
break;
case 4:
if (!write_alpha) {
for (k=0; k < 3; ++k)
px[k] = bg[k] + ((d[k] - bg[k]) * d[3])/255;
writef(f, "111", px[1-rgb_dir],px[1],px[1+rgb_dir]);
break;
}
/* FALLTHROUGH */
case 3:
writef(f, "111", d[1-rgb_dir],d[1],d[1+rgb_dir]);
break;
}
if (write_alpha > 0)
fwrite(&d[comp-1], 1, 1, f);
}
fwrite(&zero,scanline_pad,1,f);
}
}
static int outfile(char *filename, int rgb_dir, int vdir, int x, int y, int comp, void *data, int alpha, int pad, char *fmt, ...)
{
FILE *f = fopen(filename, "wb");
if (f) {
va_list v;
va_start(v, fmt);
writefv(f, fmt, v);
va_end(v);
write_pixels(f,rgb_dir,vdir,x,y,comp,data,alpha,pad);
fclose(f);
}
return f != NULL;
}
int stbi_write_bmp(char *filename, int x, int y, int comp, void *data)
{
int pad = (-x*3) & 3;
return outfile(filename,-1,-1,x,y,comp,data,0,pad,
"11 4 22 4" "4 44 22 444444",
'B', 'M', 14+40+(x*3+pad)*y, 0,0, 14+40, // file header
40, x,y, 1,24, 0,0,0,0,0,0); // bitmap header
}
int stbi_write_tga(char *filename, int x, int y, int comp, void *data)
{
int has_alpha = !(comp & 1);
return outfile(filename, -1,-1, x, y, comp, data, has_alpha, 0,
"111 221 2222 11", 0,0,2, 0,0,0, 0,0,x,y, 24+8*has_alpha, 8*has_alpha);
}
// any other image formats that do interleaved rgb data?
// PNG: requires adler32,crc32 -- significant amount of code
// PSD: no, channels output separately
// TIFF: no, stripwise-interleaved... i think
#endif
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