苏泊尔耗的JPEG解码器

#include "stdafx.h" #include "jpegdec2.h" #include "jpeghuff.h" #include "jpegbuf.h" #include "jpegidct.h" #include "stdio.h" #include "windows.h" #define NextByte(p) (*(p->p_data++)) #define CurByte(p) (*(p->p_data)) #define PrevByte(p) (*(--p->p_data)) #define WORD_ALIGN(p) (p) = (((p) + 1) / 2) * 2 #define DWORD_ALIGN(p) (p) = (((p) + 3) / 4) * 4 void jpeg_reset(p_jpeg_dec_rec p_rec) { p_rec->n_left_bit_count = 0; p_rec->n_reset_cnt = p_rec->n_reset_size; p_rec->i_dc = 0; p_rec->n_eob_count = 0; } BYTE jpeg_next_byte(p_jpeg_dec_rec p_rec) { BYTE b; for ( ;; ) { b = *p_rec->p_data++; if (b == 0xFF) { b = *p_rec->p_data++; if (b == 0) return 0xFF; if (b >= 0xD0 && b <= 0xD7) { /* RSTn */ jpeg_reset(p_rec); } else return b; } else return b; } return 0; } WORD jpeg_next_word(p_jpeg_dec_rec p_rec) { WORD w = (p_rec->p_data[0] << 8) | (p_rec->p_data[1]); p_rec->p_data += 2; return w; } /* 初始化解码器 */ void jpeg_init_decoder(p_jpeg_dec_rec p_rec) { p_rec->n_width = 0; p_rec->n_height = 0; p_rec->n_reset_size = 0; p_rec->left_bits = 0; p_rec->n_left_bit_count = 0; p_rec->n_horz_sample_coes_max = 0; p_rec->n_vert_sample_coes_max = 0; p_rec->n_horz_sample_coes_min = 0xff; p_rec->n_vert_sample_coes_min = 0xff; p_rec->p_bgr_buffer = NULL; p_rec->p_data = NULL; p_rec->i_dc = 0; p_rec->i_progressive = 0; p_rec->p_dus = NULL; p_rec->n_eob_count = 0; } /* 反初始化解码器 */ void jpeg_clear_up(p_jpeg_dec_rec p_rec) { } /* * 跳过下一个块 * 返回非0表示成功 */ int jpeg_skip_next_block(p_jpeg_dec_rec p_rec) { BYTE b; WORD n; b = NextByte(p_rec); if (b == 0x01 /* TEM 结束标志*/ || (b >= 0xd0 && b <= 0xd9 /* RSTn OR SOI OR EOI*/)) return 1; n = jpeg_next_word(p_rec); p_rec->p_data += (n - 2); return 1; } /* * 处理帧开始标记 * 返回非0表示成功 */ int jpeg_decode_SOF0(p_jpeg_dec_rec p_rec) { BYTE b, index, n; /* skip tag */ NextByte(p_rec); jpeg_next_word(p_rec); /* 采样精度 */ p_rec->n_bits_per_sample = NextByte(p_rec); /* 图像高度（为0表示通过DNL标记指定） */ p_rec->n_height = jpeg_next_word(p_rec); /* 图像宽度 */ p_rec->n_width = jpeg_next_word(p_rec); /* 每行字节数 */ p_rec->n_bytes_per_line = ((DWORD)p_rec->n_width) * 3; DWORD_ALIGN(p_rec->n_bytes_per_line); /* 分量数 */ p_rec->n_components = NextByte(p_rec); if (p_rec->n_components <= 0 || p_rec->n_components > 4) return 0; /* 不支持的分量数 */ for ( n = 0; n < p_rec->n_components; ++n ) { /* 分量ID */ p_rec->i_component_ids[n] = jpeg_next_byte(p_rec); /* * Note!!!! * Our index here doesn't mean component ids, its only an index * We also reference our huffman-table & quanlity-table by index not by component id. */ index = n; if ( index >= p_rec->n_components ) return 0; /* 出现了错误的分量ID */ b = jpeg_next_byte(p_rec); /* 分量采样率 */ p_rec->n_vert_sample_coes[index] = b & 0xf; p_rec->n_horz_sample_coes[index] = b >> 4; /* 计算分量采样率最大值 */ if (p_rec->n_vert_sample_coes[index] > p_rec->n_vert_sample_coes_max) p_rec->n_vert_sample_coes_max = p_rec->n_vert_sample_coes[index]; if (p_rec->n_horz_sample_coes[index] > p_rec->n_horz_sample_coes_max) p_rec->n_horz_sample_coes_max = p_rec->n_horz_sample_coes[index]; if (p_rec->n_vert_sample_coes[index] < p_rec->n_vert_sample_coes_min) p_rec->n_vert_sample_coes_min = p_rec->n_vert_sample_coes[index]; if (p_rec->n_horz_sample_coes[index] < p_rec->n_horz_sample_coes_min) p_rec->n_horz_sample_coes_min = p_rec->n_horz_sample_coes[index]; b = jpeg_next_byte(p_rec); if (b >= 4) return 0; /* 出现了错误的量化表ID */ p_rec->n_quality_table_indexes[index] = b; } return 1; } /* * 处理定义重启动段标志 * 返回非0表示成功 */ int jpeg_decode_DRI(p_jpeg_dec_rec p_rec) { NextByte(p_rec); jpeg_next_word(p_rec); p_rec->n_reset_size = jpeg_next_word(p_rec); p_rec->n_reset_cnt = p_rec->n_reset_size; return 1; } /* * 处理定义量化表标志 */ int jpeg_decode_DQT(p_jpeg_dec_rec p_rec) { WORD size; BYTE b, index, coe; WORD i; NextByte(p_rec); size = jpeg_next_word(p_rec) - 2; while ( size > 0 ) { b = jpeg_next_byte(p_rec); index = b & 0xf; if ( index >= 4 ) return 0; /* 出现了非法的量化表ID */ coe = b >> 4; if ( coe != 0 ) coe = 1; /* 量化表精度，0：8位 非0：16位 */ p_rec->quality_tables[index].precision = coe; if ( coe == 0 ) { /* 8位量化表 */ for ( i = 0; i != 64; ++i ) { p_rec->quality_tables[index].values[i] = jpeg_next_byte(p_rec); } p_rec->quality_tables[index].process_in_idct = 0; jpeg_idct_prepare_qualitytable(&p_rec->quality_tables[index]); size -= (64 + 1); } else { /* 16位量化表 */ for ( i = 0; i != 64; ++i ) { p_rec->quality_tables[index].values[i] = jpeg_next_word(p_rec); } p_rec->quality_tables[index].process_in_idct = 0; jpeg_idct_prepare_qualitytable(&p_rec->quality_tables[index]); size -= (64 * 2 + 1); } } return 1; } /* * 生成解码用哈夫曼表 */ void jpeg_make_huff_table(p_jpeg_huff_table p_table) { WORD mask; WORD i, j, k; p_table->huff_min_codes[0] = 0; for ( i = 0, mask = 0, j = 0, k = 0; i < p_table->n_code_count; ) { if ( j >= p_table->n_counts[k] ) { if ( j == 0 ) { /* 无k位Huffman码，则置huff_max_codes[k]为0、huff_min_codes[k]为0xffff以示区别 */ p_table->huff_min_codes[k] = 0xffff; p_table->huff_max_codes[k] = 0; } else { j = 0; } mask <<= 1; ++k; if ( k < 16 ) p_table->huff_min_codes[k] = mask; } else { p_table->huff_max_codes[k] = mask; ++mask; ++j; ++i; } } /* end of for(...) */ } /* * 处理定义哈夫曼表标志 */ int jpeg_decode_DHT(p_jpeg_dec_rec p_rec) { BYTE b, index, type; WORD size, total, i; NextByte(p_rec); size = jpeg_next_word(p_rec) - 2; while ( size > 0 ) { b = jpeg_next_byte(p_rec); index = b & 0xf; if (index >= 4) return 0; /* 出现了非法的哈夫曼表ID */ type = b >> 4; if (type > 1) return 0; /* 非法的哈夫曼表类型 */ total = 0; for ( i = 0; i < 16; ++i ) { b = jpeg_next_byte(p_rec); p_rec->huff_tables[type][index].n_counts[i] = b; p_rec->huff_tables[type][index].start_code_indexes[i] = (BYTE)total; total += b; } p_rec->huff_tables[type][index].n_code_count = total; memcpy(p_rec->huff_tables[type][index].codes, p_rec->p_data, total); jpeg_make_huff_table( &(p_rec->huff_tables[type][index]) ); p_rec->p_data += total; if ( p_rec->p_data >= p_rec->p_data_limit ) return 0; /* 数据不够 */ size -= (total + 16 + 1); } return 1; } /* * 查找EOI标记。找到返回非0 */ int jpeg_scan_for_eoi( p_jpeg_dec_rec p_rec ) { BYTE *p = p_rec->p_data; for ( ;; ) { if ( p + 1 >= p_rec->p_data_limit ) break; if ( *p == 0xff ) { if ( p[1] == 0xD9 ) break; else { if ( p[1] >= 0xD0 && p[1] <= 0xD7 ) { /* RSTn */ p += 2; } else if ( p[1] == 0 ) { return 0; } else { jpeg_decode_next_block(p_rec); } } } else { return 0; } } return 1; } /* * 解码帧(非渐近方式) * 返回非0表示成功 */ int jpeg_decode_scanlines(p_jpeg_dec_rec p_rec) { static BYTE _un_zig_zag[64] = { 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 }; /* 工作矩阵(Data Unit) */ SHORT du[64]; /* 指向当前量化表数值 */ DWORD *pw_quality_values; /* 各组件DC分量值 */ SHORT dc[5] = { 0, 0, 0, 0, 0 }; /* 各组件缓冲区，需释放 */ BYTE* p_com_bufs[5] = { NULL, NULL, NULL, NULL, NULL }; /* 每段每组件扫描完后地址偏移量，需释放 */