X-Git-Url: https://git.sesse.net/?p=fjl;a=blobdiff_plain;f=driver.c;h=6dcc8b3da676161ecd60e05898a27ebe3d19bf3f;hp=06d94d99d553e6aa4e784e22cfc99a4d19216df5;hb=75e1e46dafe538990da0ea3b021c82d5ed6d5e21;hpb=8445e04bae016b6bd74705902972e66ae7fe37c1 diff --git a/driver.c b/driver.c index 06d94d9..6dcc8b3 100644 --- a/driver.c +++ b/driver.c @@ -15,10 +15,12 @@ struct jpeg_image { unsigned num_components; unsigned hsample[256], vsample[256], qtable[256]; unsigned max_hsample, max_vsample; + unsigned stride[256]; unsigned num_blocks_horizontal, num_blocks_vertical; uint32_t qvalues[256][DCTSIZE2]; void* idct_data[256]; uint8_t* pixel_data[256]; + uint8_t* pixel_write_pointer[256]; }; ssize_t stdio_read(void* userdata, uint8_t* buf, size_t count) @@ -103,13 +105,59 @@ void read_sof(struct byte_source* source, struct jpeg_image* image) unsigned width = image->num_blocks_horizontal * image->hsample[c] * DCTSIZE; unsigned height = image->num_blocks_vertical * image->vsample[c] * DCTSIZE; + image->stride[c] = width; image->pixel_data[c] = (uint8_t*)malloc(width * height); assert(image->pixel_data[c] != NULL); + image->pixel_write_pointer[c] = image->pixel_data[c]; fprintf(stderr, "Component %u: allocating %d x %d\n", c, width, height); } } +void decode_ac_coefficients(const struct huffman_table* tbl, struct bit_source* bits, int16_t* coeff) +{ + for (unsigned i = 1; i < DCTSIZE2; ++i) { + possibly_refill(bits, DEHUF_AC_TABLE_BITS); + unsigned lookup = peek_bits(bits, DEHUF_AC_TABLE_BITS); + int code = tbl->ac_table_codes[lookup]; + + if (__builtin_expect(code == AC_DEHUF_SLOW_PATH, 0)) { + unsigned rs = read_huffman_symbol_no_refill(tbl, bits); + unsigned r = rs >> 4; + unsigned s = rs & 0xf; + i += r; + possibly_refill(bits, s); + + if (rs == 0x00) { + assert(code == AC_DEHUF_SLOW_PATH || code == AC_END_OF_BLOCK); + /* end of block */ + break; + } + if (rs == 0xf0) { + assert(code == AC_DEHUF_SLOW_PATH || code == AC_SIXTEEN_ZEROS); + /* 16 zero coefficients */ + continue; + } + + coeff[unzigzag[i]] = extend(read_bits(bits, s), s); + } else { + unsigned length = tbl->ac_table_length[lookup]; + int r = tbl->ac_table_skip[lookup]; + assert(r >= 0); + i += r; + assert(bits->bits_available >= length); + read_bits(bits, length); + if (code == AC_END_OF_BLOCK) { + break; + } + if (code == AC_SIXTEEN_ZEROS) { + continue; + } + coeff[unzigzag[i]] = code; + } + } +} + void read_scan(struct byte_source* source, struct jpeg_image* image, huffman_tables_t* tables) { unsigned len = read_uint16(byte_source_input_func, source); @@ -147,18 +195,19 @@ void read_scan(struct byte_source* source, struct jpeg_image* image, huffman_tab } struct bit_source bits; - init_bit_source(&bits, byte_source_input_func, source); + init_bit_source(&bits, byte_source_input_func, 8, source); unsigned mcu_x = 0, mcu_y = 0; - for ( ;; ) { + while (!bits.source_eof) { for (unsigned c = 0; c < num_components; ++c) { unsigned cn = component_num[c]; - unsigned stride = image->num_blocks_horizontal * image->hsample[cn] * DCTSIZE; assert(image->idct_data[image->qtable[cn]] != NULL); - - for (unsigned local_yb = 0; local_yb < image->vsample[cn]; ++local_yb) { - for (unsigned local_xb = 0; local_xb < image->hsample[cn]; ++local_xb) { + + uint8_t* pixel_write_pointer_y = image->pixel_write_pointer[cn]; + for (unsigned local_yb = 0; local_yb < image->vsample[cn]; ++local_yb, pixel_write_pointer_y += image->stride[cn] * DCTSIZE) { + uint8_t* pixel_write_pointer = pixel_write_pointer_y; + for (unsigned local_xb = 0; local_xb < image->hsample[cn]; ++local_xb, pixel_write_pointer += DCTSIZE) { const struct huffman_table* dc_table = &((*tables)[DC_CLASS][dc_huffman_table[c]]); const struct huffman_table* ac_table = &((*tables)[AC_CLASS][ac_huffman_table[c]]); @@ -169,53 +218,36 @@ void read_scan(struct byte_source* source, struct jpeg_image* image, huffman_tab int16_t coeff[DCTSIZE2] = { 0 }; coeff[0] = last_dc[c]; + decode_ac_coefficients(ac_table, &bits, coeff); - // decode AC components - for (unsigned i = 1; i < DCTSIZE2; ++i) { - unsigned rs = read_huffman_symbol(ac_table, &bits); - unsigned r = rs >> 4; - unsigned s = rs & 0xf; - - if (rs == 0x00) { - /* end of block */ - break; - } - if (rs == 0xf0) { - /* 16 zero coefficients */ - i += 15; - continue; - } - i += r; - - possibly_refill(&bits, s); - coeff[unzigzag[i]] = extend(read_bits(&bits, s), s); - } - uint8_t pixdata[DCTSIZE2]; idct_choice(coeff, image->idct_data[image->qtable[cn]], pixdata); - for (unsigned y = 0; y < DCTSIZE; ++y) { - unsigned real_x = (mcu_x * image->hsample[cn] + local_xb) * DCTSIZE; - unsigned real_y = (mcu_y * image->vsample[cn] + local_yb) * DCTSIZE + y; - - memcpy(image->pixel_data[cn] + real_y * stride + real_x, - pixdata + y * DCTSIZE, - DCTSIZE); + uint8_t* dest_pixdata = pixel_write_pointer; + for (unsigned y = 0; y < DCTSIZE; ++y, dest_pixdata += image->stride[cn]) { + memcpy(dest_pixdata, pixdata + y * DCTSIZE, DCTSIZE); } } } + image->pixel_write_pointer[cn] += DCTSIZE * image->hsample[cn]; } - + if (++mcu_x == image->num_blocks_horizontal) { ++mcu_y; mcu_x = 0; + + for (unsigned c = 0; c < num_components; ++c) { + unsigned cn = component_num[c]; + image->pixel_write_pointer[cn] += (image->vsample[cn] * DCTSIZE - 1) * image->stride[cn]; + } // Some debug code. const int c = 1; if (mcu_y == image->num_blocks_vertical) { unsigned stride = image->num_blocks_horizontal * image->hsample[c] * DCTSIZE; - printf("P5\n%u %u\n255\n", stride, image->height); - fwrite(image->pixel_data[c], stride * image->height, 1, stdout); + unsigned height = image->num_blocks_vertical * image->vsample[c] * DCTSIZE; + printf("P5\n%u %u\n255\n", stride, height); + fwrite(image->pixel_data[c], stride * height, 1, stdout); } } } @@ -293,6 +325,9 @@ int main(void) case 0xd8: /* SOI */ break; + case 0xd9: + /* EOI */ + exit(0); case 0xc4: /* DHT (define Huffman tables) */ read_huffman_tables(&tables, byte_source_input_func, &source);