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SIMD with Fixed-Point

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This commit is contained in:
Anurag Thakur 2022-10-17 01:58:17 +05:30
parent bd9aba933b
commit 17d14a6cef
2 changed files with 57 additions and 32 deletions
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85
src/dense/ftdense.c
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@ -11,7 +11,7 @@
#include "ftdense.h"
#include <math.h>
#include <tmmintrin.h>
#include <immintrin.h>
#include "ftdenseerrs.h"
#define PIXEL_BITS 8
@ -419,41 +419,66 @@ dense_render_glyph( dense_worker* worker, const FT_Bitmap* target )
unsigned char* dest = target->buffer;
unsigned char* dest_end = target->buffer + worker->m_w * worker->m_h;
// __m128 offset = _mm_setzero_ps();
// __m128i mask = _mm_set1_epi32(0x0c080400);
// __m128 sign_mask = _mm_set1_ps(-0.f);
// for (int i = 0; i < worker->m_h*worker->m_w; i += 4) {
// __m128 x = _mm_load_ps(&source[i]);
// x = _mm_add_ps(x, _mm_castsi128_ps(_mm_slli_si128(_mm_castps_si128(x), 4)));
// x = _mm_add_ps(x, _mm_shuffle_ps(_mm_setzero_ps(), x, 0x40));
// x = _mm_add_ps(x, offset);
// __m128 y = _mm_andnot_ps(sign_mask, x); // fabs(x)
// y = _mm_min_ps(y, _mm_set1_ps(1.0f));
// y = _mm_mul_ps(y, _mm_set1_ps(255.0f));
// __m128i z = _mm_cvtps_epi32(y);
// z = _mm_shuffle_epi8(z, mask);
// _mm_store_ss((float *)&dest[i], (__m128)z);
// offset = _mm_shuffle_ps(x, x, _MM_SHUFFLE(3, 3, 3, 3));
// }
__m128i offset = _mm_setzero_si128();
__m128i mask = _mm_set1_epi32( 0x0c080400 );
FT20D12 valnew = 0;
//float value = 0.0f;
while ( dest < dest_end )
for (int i = 0; i < worker->m_h*worker->m_w; i += 4)
{
valnew += *source++;
// load 4 floats from source
// printf("%d\n", *source);
__m128i x = _mm_load_si128( (__m128i*)&source[i] );
if(valnew > 0){
int nnew = valnew >>4;
// bkc
x = _mm_add_epi32( x, _mm_slli_si128( x, 4 ) );
if(nnew>255)nnew=255;
*dest = (unsigned char)nnew;
}else{
*dest = 0;
}
dest++;
// more bkc
x = _mm_add_epi32(
x, _mm_castps_si128( _mm_shuffle_ps( _mm_setzero_ps(),
_mm_castsi128_ps( x ), 0x40 ) ) );
// add the prefsum of previous 4 floats to all current floats
x = _mm_add_epi32( x, offset );
// take absolute value
__m128i y = _mm_abs_epi32( x ); // fabs(x)
// cap max value to 1
y = _mm_min_epi32( y, _mm_set1_epi32( 4080 ) );
// reduce to 255
y = _mm_srli_epi32( y, 4 );
// black magic
y = _mm_shuffle_epi8( y, mask );
// for some reason, storing float in an unsigned char array works fine lol
_mm_store_ss( (float*)&dest[i], (__m128)y );
// store the current prefix sum in offset
offset = _mm_castps_si128( _mm_shuffle_ps( _mm_castsi128_ps( x ),
_mm_castsi128_ps( x ),
_MM_SHUFFLE( 3, 3, 3, 3 ) ) );
}
// FT20D12 valnew = 0;
// //float value = 0.0f;
// while ( dest < dest_end )
// {
// valnew += *source++;
// // printf("%d\n", *source);
// if(valnew > 0){
// int nnew = valnew >>4;
// if(nnew>255)nnew=255;
// *dest = (unsigned char)nnew;
// }else{
// *dest = 0;
// }
// dest++;
// }
free(worker->m_a);
return error;

4
src/dense/ftdense.h
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@ -41,8 +41,8 @@ extern "C"
#endif
typedef signed long TPos;
typedef signed long long FT26D6;
typedef signed long long FT20D12;
typedef signed long FT26D6;
typedef signed int FT20D12;
typedef struct
{