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stb_image: IDCT kernel func ptr in stbi__jpeg 

I want to support SSE2 kernels that auto-detect. If implemented
using globals, this would trigger thread race checkers if stb_image
was used in multiple threads. Just make the kernels be explicitly
per-stbi__jpeg to avoid this.

(This commit is the first step in replacing existing STBI_SIMD
functionality.)
pull/62/head
Fabian Giesen 2014-12-18 06:49:41 -08:00
parent 518306517c
commit c6a3235995
1 changed files with 12 additions and 10 deletions
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22
stb_image.h
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@ -1040,6 +1040,9 @@ typedef struct
int scan_n, order[4];
int restart_interval, todo;
// kernels
void (*idct_block_kernel)(stbi_uc *out, int out_stride, short data[64]);
} stbi__jpeg;
static int stbi__build_huffman(stbi__huffman *h, int *count)
@ -1457,11 +1460,7 @@ static int stbi__parse_entropy_coded_data(stbi__jpeg *z)
for (i=0; i < w; ++i) {
int ha = z->img_comp[n].ha;
if (!stbi__jpeg_decode_block(z, data, z->huff_dc+z->img_comp[n].hd, z->huff_ac+ha, z->fast_ac[ha], n, z->dequant[z->img_comp[n].tq])) return 0;
#ifdef STBI_SIMD
stbi__idct_installed(z->img_comp[n].data+z->img_comp[n].w2*j*8+i*8, z->img_comp[n].w2, data, stbi__dq_ones);
#else
stbi__idct_block(z->img_comp[n].data+z->img_comp[n].w2*j*8+i*8, z->img_comp[n].w2, data);
#endif
z->idct_block_kernel(z->img_comp[n].data+z->img_comp[n].w2*j*8+i*8, z->img_comp[n].w2, data);
// every data block is an MCU, so countdown the restart interval
if (--z->todo <= 0) {
if (z->code_bits < 24) stbi__grow_buffer_unsafe(z);
@ -1488,11 +1487,7 @@ static int stbi__parse_entropy_coded_data(stbi__jpeg *z)
int y2 = (j*z->img_comp[n].v + y)*8;
int ha = z->img_comp[n].ha;
if (!stbi__jpeg_decode_block(z, data, z->huff_dc+z->img_comp[n].hd, z->huff_ac+ha, z->fast_ac[ha], n, z->dequant[z->img_comp[n].tq])) return 0;
#ifdef STBI_SIMD
stbi__idct_installed(z->img_comp[n].data+z->img_comp[n].w2*y2+x2, z->img_comp[n].w2, data, stbi__dq_ones);
#else
stbi__idct_block(z->img_comp[n].data+z->img_comp[n].w2*y2+x2, z->img_comp[n].w2, data);
#endif
z->idct_block_kernel(z->img_comp[n].data+z->img_comp[n].w2*y2+x2, z->img_comp[n].w2, data);
}
}
}
@ -1863,6 +1858,11 @@ STBIDEF void stbi_install_YCbCr_to_RGB(stbi_YCbCr_to_RGB_run func)
}
#endif
// set up the kernels
static void stbi__setup_jpeg(stbi__jpeg *j)
{
j->idct_block_kernel = stbi__idct_block;
}
// clean up the temporary component buffers
static void stbi__cleanup_jpeg(stbi__jpeg *j)
@ -1996,6 +1996,7 @@ static unsigned char *stbi__jpeg_load(stbi__context *s, int *x, int *y, int *com
{
stbi__jpeg j;
j.s = s;
stbi__setup_jpeg(&j);
return load_jpeg_image(&j, x,y,comp,req_comp);
}
@ -2004,6 +2005,7 @@ static int stbi__jpeg_test(stbi__context *s)
int r;
stbi__jpeg j;
j.s = s;
stbi__setup_jpeg(&j);
r = decode_jpeg_header(&j, SCAN_type);
stbi__rewind(s);
return r;