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https://github.com/nothings/stb
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VC6:
support using inline asm for cpuid YCbCr: switch SSE code to constants that match old C; create C version that is same as SSE; tiny optimization(?) of SSE
This commit is contained in:
Sean Barrett
parent
b082091bcb
commit
f259bf27e9
99
stb_image.h
99
stb_image.h
@ -81,7 +81,8 @@
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// Limitations:
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// - no jpeg progressive support
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// - non-HDR formats support 8-bit samples only (jpeg, png)
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// - no 16-bit-per-channel PNG
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// - no 12-bit-per-channel jpeg
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// - no delayed line count (jpeg) -- IJG doesn't support either
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// - no 1-bit BMP
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// - GIF always returns *comp=4
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@ -196,8 +197,12 @@
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//
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// SIMD support
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//
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// The JPEG decoder will automatically use SIMD kernels where supported,
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// replacing the STBI_SIMD-do-it-yourself interface from previous versions.
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// The JPEG decoder will automatically use SIMD kernels on x86 platforms
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// where supported.
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//
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// (The old do-it-yourself SIMD API is no longer supported in the current
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// code.)
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//
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// The code will automatically detect if the required SIMD instructions are
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// available, and fall back to the generic C version where they're not.
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//
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@ -402,16 +407,35 @@ typedef unsigned char validate_uint32[sizeof(stbi__uint32)==4 ? 1 : -1];
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#include <emmintrin.h>
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#ifdef _MSC_VER
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#if _MSC_VER >= 1400 // not VC6
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#include <intrin.h> // __cpuid
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static int stbi__cpuid3(void)
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{
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int info[4];
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__cpuid(info,1);
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return info[3];
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}
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#else
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static int stbi__cpuid3(void)
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{
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int res;
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__asm {
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mov eax,1
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cpuid
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mov res,edx
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}
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return res;
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}
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#endif
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#define STBI_SIMD_ALIGN(type, name) __declspec(align(16)) type name
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static int stbi__sse2_available()
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{
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int info[4];
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__cpuid(info, 1);
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return ((info[3] >> 26) & 1) != 0;
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int info3 = stbi__cpuid3();
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return ((info3 >> 26) & 1) != 0;
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}
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#else // assume GCC-style if not VC++
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#define STBI_SIMD_ALIGN(type, name) type name __attribute__((aligned(16)))
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@ -2117,6 +2141,35 @@ static void stbi__YCbCr_to_RGB_row(stbi_uc *out, const stbi_uc *y, const stbi_uc
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}
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}
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#define float2fixed2(x) (((int) ((x) * 4096.0f + 0.5f)) << 8)
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static void stbi__YCbCr_to_RGB_backport(stbi_uc *out, const stbi_uc *y, const stbi_uc *pcb, const stbi_uc *pcr, int count, int step)
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{
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int i;
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for (i=0; i < count; ++i) {
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int y_fixed = (y[i] << 20) + (1<<19); // rounding
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int r,g,b;
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int cr = pcr[i] - 128;
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int cb = pcb[i] - 128;
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r = y_fixed + cr*float2fixed2(1.40200f);
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g = y_fixed;
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g += (cr*-float2fixed2(0.71414f)) & 0xffff0000;
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g += (cb*-float2fixed2(0.34414f)) & 0xffff0000;
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b = y_fixed + cb*float2fixed2(1.77200f);
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r >>= 20;
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g >>= 20;
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b >>= 20;
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if ((unsigned) r > 255) { if (r < 0) r = 0; else r = 255; }
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if ((unsigned) g > 255) { if (g < 0) g = 0; else g = 255; }
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if ((unsigned) b > 255) { if (b < 0) b = 0; else b = 255; }
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out[0] = (stbi_uc)r;
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out[1] = (stbi_uc)g;
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out[2] = (stbi_uc)b;
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out[3] = 255;
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out += step;
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}
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}
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#ifdef STBI_SSE2
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static void stbi__YCbCr_to_RGB_sse2(stbi_uc *out, stbi_uc const *y, stbi_uc const *pcb, stbi_uc const *pcr, int count, int step)
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{
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@ -2130,37 +2183,35 @@ static void stbi__YCbCr_to_RGB_sse2(stbi_uc *out, stbi_uc const *y, stbi_uc cons
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if (step == 4) {
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// this is a fairly straightforward implementation and not super-optimized.
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__m128i signflip = _mm_set1_epi8(-0x80);
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__m128i cr_const0 = _mm_set1_epi16((short) ( 1.40200f*4096.0f));
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__m128i cr_const1 = _mm_set1_epi16((short) (-0.71414f*4096.0f));
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__m128i cb_const0 = _mm_set1_epi16((short) (-0.34414f*4096.0f));
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__m128i cb_const1 = _mm_set1_epi16((short) ( 1.77200f*4096.0f));
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__m128i y_bias = _mm_set1_epi16(8);
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__m128i xw = _mm_set1_epi16(255);
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__m128i cr_const0 = _mm_set1_epi16( (short) ( 1.40200f*4096.0f+0.5f));
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__m128i cr_const1 = _mm_set1_epi16( - (short) ( 0.71414f*4096.0f+0.5f));
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__m128i cb_const0 = _mm_set1_epi16( - (short) ( 0.34414f*4096.0f+0.5f));
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__m128i cb_const1 = _mm_set1_epi16( (short) ( 1.77200f*4096.0f+0.5f));
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__m128i y_bias = _mm_set1_epi8((char) 128);
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__m128i xw = _mm_set1_epi16(255); // alpha channel
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for (; i+7 < count; i += 8) {
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// load
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__m128i zero = _mm_setzero_si128();
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__m128i y_bytes = _mm_loadl_epi64((__m128i *) (y+i));
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__m128i cr_bytes = _mm_loadl_epi64((__m128i *) (pcr+i));
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__m128i cb_bytes = _mm_loadl_epi64((__m128i *) (pcb+i));
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__m128i cr_bias = _mm_xor_si128(cr_bytes, signflip); // -128
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__m128i cb_bias = _mm_xor_si128(cb_bytes, signflip); // -128
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__m128i cr_biased = _mm_xor_si128(cr_bytes, signflip); // -128
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__m128i cb_biased = _mm_xor_si128(cb_bytes, signflip); // -128
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// unpack to short (and left-shift cr, cb by 8)
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__m128i yw = _mm_unpacklo_epi8(y_bytes, zero);
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__m128i crw = _mm_unpacklo_epi8(_mm_setzero_si128(), cr_bias);
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__m128i cbw = _mm_unpacklo_epi8(_mm_setzero_si128(), cb_bias);
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__m128i yw = _mm_unpacklo_epi8(y_bias, y_bytes);
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__m128i crw = _mm_unpacklo_epi8(_mm_setzero_si128(), cr_biased);
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__m128i cbw = _mm_unpacklo_epi8(_mm_setzero_si128(), cb_biased);
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// color transform
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__m128i yws = _mm_slli_epi16(yw, 4);
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__m128i yws = _mm_srli_epi16(yw, 4);
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__m128i cr0 = _mm_mulhi_epi16(cr_const0, crw);
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__m128i cb0 = _mm_mulhi_epi16(cb_const0, cbw);
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__m128i ywb = _mm_add_epi16(yws, y_bias);
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__m128i cb1 = _mm_mulhi_epi16(cbw, cb_const1);
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__m128i cr1 = _mm_mulhi_epi16(crw, cr_const1);
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__m128i rws = _mm_add_epi16(cr0, ywb);
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__m128i gwt = _mm_add_epi16(cb0, ywb);
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__m128i bws = _mm_add_epi16(ywb, cb1);
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__m128i rws = _mm_add_epi16(cr0, yws);
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__m128i gwt = _mm_add_epi16(cb0, yws);
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__m128i bws = _mm_add_epi16(yws, cb1);
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__m128i gws = _mm_add_epi16(gwt, cr1);
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// descale
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@ -9,9 +9,48 @@
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#define PNGSUITE_PRIMARY
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#if 1
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void test_ycbcr(void)
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{
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STBI_SIMD_ALIGN(unsigned char, y[256]);
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STBI_SIMD_ALIGN(unsigned char, cb[256]);
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STBI_SIMD_ALIGN(unsigned char, cr[256]);
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STBI_SIMD_ALIGN(unsigned char, out1[256][4]);
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STBI_SIMD_ALIGN(unsigned char, out2[256][4]);
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int i,j,k;
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int count = 0, bigcount=0;
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for (i=0; i < 256; ++i) {
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for (j=0; j < 256; ++j) {
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for (k=0; k < 256; ++k) {
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y[k] = k;
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cb[k] = j;
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cr[k] = i;
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}
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stbi__YCbCr_to_RGB_sse2(out1[0], y, cb, cr, 256, 4);
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stbi__YCbCr_to_RGB_backport(out2[0], y, cb, cr, 256, 4);
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for (k=0; k < 256; ++k) {
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if (out1[k][0] != out2[k][0] || out1[k][1] != out2[k][1] || out1[k][2] != out2[k][2]) {
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int dist1 = abs(out1[k][0] - out2[k][0]);
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int dist2 = abs(out1[k][1] - out2[k][1]);
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int dist3 = abs(out1[k][2] - out2[k][2]);
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++count;
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if (dist2)
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++bigcount;
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}
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}
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}
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printf("So far: %d (%d big)\n", count, bigcount);
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}
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printf("Final: %d (%d big)\n", count, bigcount);
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}
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#endif
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int main(int argc, char **argv)
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{
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int w,h;
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test_ycbcr();
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if (argc > 1) {
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int i;
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for (i=1; i < argc; ++i) {
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