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jpgd.cpp
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// jpgd.cpp - C++ class for JPEG decompression.
// Public domain, Rich Geldreich <richgel99@gmail.com>
// Alex Evans: Linear memory allocator (taken from jpge.h).
// v1.04, May. 19, 2012: Code tweaks to fix VS2008 static code analysis warnings (all looked harmless)
//
// Supports progressive and baseline sequential JPEG image files, and the most common chroma subsampling factors: Y, H1V1, H2V1, H1V2, and H2V2.
//
// Chroma upsampling quality: H2V2 is upsampled in the frequency domain, H2V1 and H1V2 are upsampled using point sampling.
// Chroma upsampling reference: "Fast Scheme for Image Size Change in the Compressed Domain"
// http://vision.ai.uiuc.edu/~dugad/research/dct/index.html
#include "jpgd.h"
#include <string.h>
#include <assert.h>
#define JPGD_ASSERT(x) assert(x)
#ifdef _MSC_VER
#pragma warning (disable : 4611) // warning C4611: interaction between '_setjmp' and C++ object destruction is non-portable
#endif
// Set to 1 to enable freq. domain chroma upsampling on images using H2V2 subsampling (0=faster nearest neighbor sampling).
// This is slower, but results in higher quality on images with highly saturated colors.
#define JPGD_SUPPORT_FREQ_DOMAIN_UPSAMPLING 1
#define JPGD_TRUE (1)
#define JPGD_FALSE (0)
#define JPGD_MAX(a,b) (((a)>(b)) ? (a) : (b))
#define JPGD_MIN(a,b) (((a)<(b)) ? (a) : (b))
namespace jpgd {
static inline void *jpgd_malloc(size_t nSize) { return malloc(nSize); }
static inline void jpgd_free(void *p) { free(p); }
// DCT coefficients are stored in this sequence.
static int g_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 };
enum JPEG_MARKER
{
M_SOF0 = 0xC0, M_SOF1 = 0xC1, M_SOF2 = 0xC2, M_SOF3 = 0xC3, M_SOF5 = 0xC5, M_SOF6 = 0xC6, M_SOF7 = 0xC7, M_JPG = 0xC8,
M_SOF9 = 0xC9, M_SOF10 = 0xCA, M_SOF11 = 0xCB, M_SOF13 = 0xCD, M_SOF14 = 0xCE, M_SOF15 = 0xCF, M_DHT = 0xC4, M_DAC = 0xCC,
M_RST0 = 0xD0, M_RST1 = 0xD1, M_RST2 = 0xD2, M_RST3 = 0xD3, M_RST4 = 0xD4, M_RST5 = 0xD5, M_RST6 = 0xD6, M_RST7 = 0xD7,
M_SOI = 0xD8, M_EOI = 0xD9, M_SOS = 0xDA, M_DQT = 0xDB, M_DNL = 0xDC, M_DRI = 0xDD, M_DHP = 0xDE, M_EXP = 0xDF,
M_APP0 = 0xE0, M_APP15 = 0xEF, M_JPG0 = 0xF0, M_JPG13 = 0xFD, M_COM = 0xFE, M_TEM = 0x01, M_ERROR = 0x100, RST0 = 0xD0
};
enum JPEG_SUBSAMPLING { JPGD_GRAYSCALE = 0, JPGD_YH1V1, JPGD_YH2V1, JPGD_YH1V2, JPGD_YH2V2 };
#define CONST_BITS 13
#define PASS1_BITS 2
#define SCALEDONE ((int32)1)
#define FIX_0_298631336 ((int32)2446) /* FIX(0.298631336) */
#define FIX_0_390180644 ((int32)3196) /* FIX(0.390180644) */
#define FIX_0_541196100 ((int32)4433) /* FIX(0.541196100) */
#define FIX_0_765366865 ((int32)6270) /* FIX(0.765366865) */
#define FIX_0_899976223 ((int32)7373) /* FIX(0.899976223) */
#define FIX_1_175875602 ((int32)9633) /* FIX(1.175875602) */
#define FIX_1_501321110 ((int32)12299) /* FIX(1.501321110) */
#define FIX_1_847759065 ((int32)15137) /* FIX(1.847759065) */
#define FIX_1_961570560 ((int32)16069) /* FIX(1.961570560) */
#define FIX_2_053119869 ((int32)16819) /* FIX(2.053119869) */
#define FIX_2_562915447 ((int32)20995) /* FIX(2.562915447) */
#define FIX_3_072711026 ((int32)25172) /* FIX(3.072711026) */
#define DESCALE(x,n) (((x) + (SCALEDONE << ((n)-1))) >> (n))
#define DESCALE_ZEROSHIFT(x,n) (((x) + (128 << (n)) + (SCALEDONE << ((n)-1))) >> (n))
#define MULTIPLY(var, cnst) ((var) * (cnst))
#define CLAMP(i) ((static_cast<uint>(i) > 255) ? (((~i) >> 31) & 0xFF) : (i))
// Compiler creates a fast path 1D IDCT for X non-zero columns
template <int NONZERO_COLS>
struct Row
{
static void idct(int* pTemp, const jpgd_block_t* pSrc)
{
// ACCESS_COL() will be optimized at compile time to either an array access, or 0.
#define ACCESS_COL(x) (((x) < NONZERO_COLS) ? (int)pSrc[x] : 0)
const int z2 = ACCESS_COL(2), z3 = ACCESS_COL(6);
const int z1 = MULTIPLY(z2 + z3, FIX_0_541196100);
const int tmp2 = z1 + MULTIPLY(z3, - FIX_1_847759065);
const int tmp3 = z1 + MULTIPLY(z2, FIX_0_765366865);
const int tmp0 = (ACCESS_COL(0) + ACCESS_COL(4)) << CONST_BITS;
const int tmp1 = (ACCESS_COL(0) - ACCESS_COL(4)) << CONST_BITS;
const int tmp10 = tmp0 + tmp3, tmp13 = tmp0 - tmp3, tmp11 = tmp1 + tmp2, tmp12 = tmp1 - tmp2;
const int atmp0 = ACCESS_COL(7), atmp1 = ACCESS_COL(5), atmp2 = ACCESS_COL(3), atmp3 = ACCESS_COL(1);
const int bz1 = atmp0 + atmp3, bz2 = atmp1 + atmp2, bz3 = atmp0 + atmp2, bz4 = atmp1 + atmp3;
const int bz5 = MULTIPLY(bz3 + bz4, FIX_1_175875602);
const int az1 = MULTIPLY(bz1, - FIX_0_899976223);
const int az2 = MULTIPLY(bz2, - FIX_2_562915447);
const int az3 = MULTIPLY(bz3, - FIX_1_961570560) + bz5;
const int az4 = MULTIPLY(bz4, - FIX_0_390180644) + bz5;
const int btmp0 = MULTIPLY(atmp0, FIX_0_298631336) + az1 + az3;
const int btmp1 = MULTIPLY(atmp1, FIX_2_053119869) + az2 + az4;
const int btmp2 = MULTIPLY(atmp2, FIX_3_072711026) + az2 + az3;
const int btmp3 = MULTIPLY(atmp3, FIX_1_501321110) + az1 + az4;
pTemp[0] = DESCALE(tmp10 + btmp3, CONST_BITS-PASS1_BITS);
pTemp[7] = DESCALE(tmp10 - btmp3, CONST_BITS-PASS1_BITS);
pTemp[1] = DESCALE(tmp11 + btmp2, CONST_BITS-PASS1_BITS);
pTemp[6] = DESCALE(tmp11 - btmp2, CONST_BITS-PASS1_BITS);
pTemp[2] = DESCALE(tmp12 + btmp1, CONST_BITS-PASS1_BITS);
pTemp[5] = DESCALE(tmp12 - btmp1, CONST_BITS-PASS1_BITS);
pTemp[3] = DESCALE(tmp13 + btmp0, CONST_BITS-PASS1_BITS);
pTemp[4] = DESCALE(tmp13 - btmp0, CONST_BITS-PASS1_BITS);
}
};
template <>
struct Row<0>
{
static void idct(int* pTemp, const jpgd_block_t* pSrc)
{
(void)pTemp;
(void)pSrc;
#ifdef _MSC_VER
pTemp; pSrc;
#endif
}
};
template <>
struct Row<1>
{
static void idct(int* pTemp, const jpgd_block_t* pSrc)
{
const int dcval = (pSrc[0] << PASS1_BITS);
pTemp[0] = dcval;
pTemp[1] = dcval;
pTemp[2] = dcval;
pTemp[3] = dcval;
pTemp[4] = dcval;
pTemp[5] = dcval;
pTemp[6] = dcval;
pTemp[7] = dcval;
}
};
// Compiler creates a fast path 1D IDCT for X non-zero rows
template <int NONZERO_ROWS>
struct Col
{
static void idct(uint8* pDst_ptr, const int* pTemp)
{
// ACCESS_ROW() will be optimized at compile time to either an array access, or 0.
#define ACCESS_ROW(x) (((x) < NONZERO_ROWS) ? pTemp[x * 8] : 0)
const int z2 = ACCESS_ROW(2);
const int z3 = ACCESS_ROW(6);
const int z1 = MULTIPLY(z2 + z3, FIX_0_541196100);
const int tmp2 = z1 + MULTIPLY(z3, - FIX_1_847759065);
const int tmp3 = z1 + MULTIPLY(z2, FIX_0_765366865);
const int tmp0 = (ACCESS_ROW(0) + ACCESS_ROW(4)) << CONST_BITS;
const int tmp1 = (ACCESS_ROW(0) - ACCESS_ROW(4)) << CONST_BITS;
const int tmp10 = tmp0 + tmp3, tmp13 = tmp0 - tmp3, tmp11 = tmp1 + tmp2, tmp12 = tmp1 - tmp2;
const int atmp0 = ACCESS_ROW(7), atmp1 = ACCESS_ROW(5), atmp2 = ACCESS_ROW(3), atmp3 = ACCESS_ROW(1);
const int bz1 = atmp0 + atmp3, bz2 = atmp1 + atmp2, bz3 = atmp0 + atmp2, bz4 = atmp1 + atmp3;
const int bz5 = MULTIPLY(bz3 + bz4, FIX_1_175875602);
const int az1 = MULTIPLY(bz1, - FIX_0_899976223);
const int az2 = MULTIPLY(bz2, - FIX_2_562915447);
const int az3 = MULTIPLY(bz3, - FIX_1_961570560) + bz5;
const int az4 = MULTIPLY(bz4, - FIX_0_390180644) + bz5;
const int btmp0 = MULTIPLY(atmp0, FIX_0_298631336) + az1 + az3;
const int btmp1 = MULTIPLY(atmp1, FIX_2_053119869) + az2 + az4;
const int btmp2 = MULTIPLY(atmp2, FIX_3_072711026) + az2 + az3;
const int btmp3 = MULTIPLY(atmp3, FIX_1_501321110) + az1 + az4;
int i = DESCALE_ZEROSHIFT(tmp10 + btmp3, CONST_BITS+PASS1_BITS+3);
pDst_ptr[8*0] = (uint8)CLAMP(i);
i = DESCALE_ZEROSHIFT(tmp10 - btmp3, CONST_BITS+PASS1_BITS+3);
pDst_ptr[8*7] = (uint8)CLAMP(i);
i = DESCALE_ZEROSHIFT(tmp11 + btmp2, CONST_BITS+PASS1_BITS+3);
pDst_ptr[8*1] = (uint8)CLAMP(i);
i = DESCALE_ZEROSHIFT(tmp11 - btmp2, CONST_BITS+PASS1_BITS+3);
pDst_ptr[8*6] = (uint8)CLAMP(i);
i = DESCALE_ZEROSHIFT(tmp12 + btmp1, CONST_BITS+PASS1_BITS+3);
pDst_ptr[8*2] = (uint8)CLAMP(i);
i = DESCALE_ZEROSHIFT(tmp12 - btmp1, CONST_BITS+PASS1_BITS+3);
pDst_ptr[8*5] = (uint8)CLAMP(i);
i = DESCALE_ZEROSHIFT(tmp13 + btmp0, CONST_BITS+PASS1_BITS+3);
pDst_ptr[8*3] = (uint8)CLAMP(i);
i = DESCALE_ZEROSHIFT(tmp13 - btmp0, CONST_BITS+PASS1_BITS+3);
pDst_ptr[8*4] = (uint8)CLAMP(i);
}
};
template <>
struct Col<1>
{
static void idct(uint8* pDst_ptr, const int* pTemp)
{
int dcval = DESCALE_ZEROSHIFT(pTemp[0], PASS1_BITS+3);
const uint8 dcval_clamped = (uint8)CLAMP(dcval);
pDst_ptr[0*8] = dcval_clamped;
pDst_ptr[1*8] = dcval_clamped;
pDst_ptr[2*8] = dcval_clamped;
pDst_ptr[3*8] = dcval_clamped;
pDst_ptr[4*8] = dcval_clamped;
pDst_ptr[5*8] = dcval_clamped;
pDst_ptr[6*8] = dcval_clamped;
pDst_ptr[7*8] = dcval_clamped;
}
};
static const uint8 s_idct_row_table[] =
{
1,0,0,0,0,0,0,0, 2,0,0,0,0,0,0,0, 2,1,0,0,0,0,0,0, 2,1,1,0,0,0,0,0, 2,2,1,0,0,0,0,0, 3,2,1,0,0,0,0,0, 4,2,1,0,0,0,0,0, 4,3,1,0,0,0,0,0,
4,3,2,0,0,0,0,0, 4,3,2,1,0,0,0,0, 4,3,2,1,1,0,0,0, 4,3,2,2,1,0,0,0, 4,3,3,2,1,0,0,0, 4,4,3,2,1,0,0,0, 5,4,3,2,1,0,0,0, 6,4,3,2,1,0,0,0,
6,5,3,2,1,0,0,0, 6,5,4,2,1,0,0,0, 6,5,4,3,1,0,0,0, 6,5,4,3,2,0,0,0, 6,5,4,3,2,1,0,0, 6,5,4,3,2,1,1,0, 6,5,4,3,2,2,1,0, 6,5,4,3,3,2,1,0,
6,5,4,4,3,2,1,0, 6,5,5,4,3,2,1,0, 6,6,5,4,3,2,1,0, 7,6,5,4,3,2,1,0, 8,6,5,4,3,2,1,0, 8,7,5,4,3,2,1,0, 8,7,6,4,3,2,1,0, 8,7,6,5,3,2,1,0,
8,7,6,5,4,2,1,0, 8,7,6,5,4,3,1,0, 8,7,6,5,4,3,2,0, 8,7,6,5,4,3,2,1, 8,7,6,5,4,3,2,2, 8,7,6,5,4,3,3,2, 8,7,6,5,4,4,3,2, 8,7,6,5,5,4,3,2,
8,7,6,6,5,4,3,2, 8,7,7,6,5,4,3,2, 8,8,7,6,5,4,3,2, 8,8,8,6,5,4,3,2, 8,8,8,7,5,4,3,2, 8,8,8,7,6,4,3,2, 8,8,8,7,6,5,3,2, 8,8,8,7,6,5,4,2,
8,8,8,7,6,5,4,3, 8,8,8,7,6,5,4,4, 8,8,8,7,6,5,5,4, 8,8,8,7,6,6,5,4, 8,8,8,7,7,6,5,4, 8,8,8,8,7,6,5,4, 8,8,8,8,8,6,5,4, 8,8,8,8,8,7,5,4,
8,8,8,8,8,7,6,4, 8,8,8,8,8,7,6,5, 8,8,8,8,8,7,6,6, 8,8,8,8,8,7,7,6, 8,8,8,8,8,8,7,6, 8,8,8,8,8,8,8,6, 8,8,8,8,8,8,8,7, 8,8,8,8,8,8,8,8,
};
static const uint8 s_idct_col_table[] = { 1, 1, 2, 3, 3, 3, 3, 3, 3, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8 };
void idct(const jpgd_block_t* pSrc_ptr, uint8* pDst_ptr, int block_max_zag)
{
JPGD_ASSERT(block_max_zag >= 1);
JPGD_ASSERT(block_max_zag <= 64);
if (block_max_zag <= 1)
{
int k = ((pSrc_ptr[0] + 4) >> 3) + 128;
k = CLAMP(k);
k = k | (k<<8);
k = k | (k<<16);
for (int i = 8; i > 0; i--)
{
*(int*)&pDst_ptr[0] = k;
*(int*)&pDst_ptr[4] = k;
pDst_ptr += 8;
}
return;
}
int temp[64];
const jpgd_block_t* pSrc = pSrc_ptr;
int* pTemp = temp;
const uint8* pRow_tab = &s_idct_row_table[(block_max_zag - 1) * 8];
int i;
for (i = 8; i > 0; i--, pRow_tab++)
{
switch (*pRow_tab)
{
case 0: Row<0>::idct(pTemp, pSrc); break;
case 1: Row<1>::idct(pTemp, pSrc); break;
case 2: Row<2>::idct(pTemp, pSrc); break;
case 3: Row<3>::idct(pTemp, pSrc); break;
case 4: Row<4>::idct(pTemp, pSrc); break;
case 5: Row<5>::idct(pTemp, pSrc); break;
case 6: Row<6>::idct(pTemp, pSrc); break;
case 7: Row<7>::idct(pTemp, pSrc); break;
case 8: Row<8>::idct(pTemp, pSrc); break;
}
pSrc += 8;
pTemp += 8;
}
pTemp = temp;
const int nonzero_rows = s_idct_col_table[block_max_zag - 1];
for (i = 8; i > 0; i--)
{
switch (nonzero_rows)
{
case 1: Col<1>::idct(pDst_ptr, pTemp); break;
case 2: Col<2>::idct(pDst_ptr, pTemp); break;
case 3: Col<3>::idct(pDst_ptr, pTemp); break;
case 4: Col<4>::idct(pDst_ptr, pTemp); break;
case 5: Col<5>::idct(pDst_ptr, pTemp); break;
case 6: Col<6>::idct(pDst_ptr, pTemp); break;
case 7: Col<7>::idct(pDst_ptr, pTemp); break;
case 8: Col<8>::idct(pDst_ptr, pTemp); break;
}
pTemp++;
pDst_ptr++;
}
}
void idct_4x4(const jpgd_block_t* pSrc_ptr, uint8* pDst_ptr)
{
int temp[64];
int* pTemp = temp;
const jpgd_block_t* pSrc = pSrc_ptr;
for (int i = 4; i > 0; i--)
{
Row<4>::idct(pTemp, pSrc);
pSrc += 8;
pTemp += 8;
}
pTemp = temp;
for (int i = 8; i > 0; i--)
{
Col<4>::idct(pDst_ptr, pTemp);
pTemp++;
pDst_ptr++;
}
}
// Retrieve one character from the input stream.
inline uint jpeg_decoder::get_char()
{
// Any bytes remaining in buffer?
if (!m_in_buf_left)
{
// Try to get more bytes.
prep_in_buffer();
// Still nothing to get?
if (!m_in_buf_left)
{
// Pad the end of the stream with 0xFF 0xD9 (EOI marker)
int t = m_tem_flag;
m_tem_flag ^= 1;
if (t)
return 0xD9;
else
return 0xFF;
}
}
uint c = *m_pIn_buf_ofs++;
m_in_buf_left--;
return c;
}
// Same as previous method, except can indicate if the character is a pad character or not.
inline uint jpeg_decoder::get_char(bool *pPadding_flag)
{
if (!m_in_buf_left)
{
prep_in_buffer();
if (!m_in_buf_left)
{
*pPadding_flag = true;
int t = m_tem_flag;
m_tem_flag ^= 1;
if (t)
return 0xD9;
else
return 0xFF;
}
}
*pPadding_flag = false;
uint c = *m_pIn_buf_ofs++;
m_in_buf_left--;
return c;
}
// Inserts a previously retrieved character back into the input buffer.
inline void jpeg_decoder::stuff_char(uint8 q)
{
*(--m_pIn_buf_ofs) = q;
m_in_buf_left++;
}
// Retrieves one character from the input stream, but does not read past markers. Will continue to return 0xFF when a marker is encountered.
inline uint8 jpeg_decoder::get_octet()
{
bool padding_flag;
int c = get_char(&padding_flag);
if (c == 0xFF)
{
if (padding_flag)
return 0xFF;
c = get_char(&padding_flag);
if (padding_flag)
{
stuff_char(0xFF);
return 0xFF;
}
if (c == 0x00)
return 0xFF;
else
{
stuff_char(static_cast<uint8>(c));
stuff_char(0xFF);
return 0xFF;
}
}
return static_cast<uint8>(c);
}
// Retrieves a variable number of bits from the input stream. Does not recognize markers.
inline uint jpeg_decoder::get_bits(int num_bits)
{
if (!num_bits)
return 0;
uint i = m_bit_buf >> (32 - num_bits);
if ((m_bits_left -= num_bits) <= 0)
{
m_bit_buf <<= (num_bits += m_bits_left);
uint c1 = get_char();
uint c2 = get_char();
m_bit_buf = (m_bit_buf & 0xFFFF0000) | (c1 << 8) | c2;
m_bit_buf <<= -m_bits_left;
m_bits_left += 16;
JPGD_ASSERT(m_bits_left >= 0);
}
else
m_bit_buf <<= num_bits;
return i;
}
// Retrieves a variable number of bits from the input stream. Markers will not be read into the input bit buffer. Instead, an infinite number of all 1's will be returned when a marker is encountered.
inline uint jpeg_decoder::get_bits_no_markers(int num_bits)
{
if (!num_bits)
return 0;
uint i = m_bit_buf >> (32 - num_bits);
if ((m_bits_left -= num_bits) <= 0)
{
m_bit_buf <<= (num_bits += m_bits_left);
if ((m_in_buf_left < 2) || (m_pIn_buf_ofs[0] == 0xFF) || (m_pIn_buf_ofs[1] == 0xFF))
{
uint c1 = get_octet();
uint c2 = get_octet();
m_bit_buf |= (c1 << 8) | c2;
}
else
{
m_bit_buf |= ((uint)m_pIn_buf_ofs[0] << 8) | m_pIn_buf_ofs[1];
m_in_buf_left -= 2;
m_pIn_buf_ofs += 2;
}
m_bit_buf <<= -m_bits_left;
m_bits_left += 16;
JPGD_ASSERT(m_bits_left >= 0);
}
else
m_bit_buf <<= num_bits;
return i;
}
// Decodes a Huffman encoded symbol.
inline int jpeg_decoder::huff_decode(huff_tables *pH)
{
int symbol;
// Check first 8-bits: do we have a complete symbol?
if ((symbol = pH->look_up[m_bit_buf >> 24]) < 0)
{
// Decode more bits, use a tree traversal to find symbol.
int ofs = 23;
do
{
symbol = pH->tree[-(int)(symbol + ((m_bit_buf >> ofs) & 1))];
ofs--;
} while (symbol < 0);
get_bits_no_markers(8 + (23 - ofs));
}
else
get_bits_no_markers(pH->code_size[symbol]);
return symbol;
}
// Decodes a Huffman encoded symbol.
inline int jpeg_decoder::huff_decode(huff_tables *pH, int& extra_bits)
{
int symbol;
// Check first 8-bits: do we have a complete symbol?
if ((symbol = pH->look_up2[m_bit_buf >> 24]) < 0)
{
// Use a tree traversal to find symbol.
int ofs = 23;
do
{
symbol = pH->tree[-(int)(symbol + ((m_bit_buf >> ofs) & 1))];
ofs--;
} while (symbol < 0);
get_bits_no_markers(8 + (23 - ofs));
extra_bits = get_bits_no_markers(symbol & 0xF);
}
else
{
JPGD_ASSERT(((symbol >> 8) & 31) == pH->code_size[symbol & 255] + ((symbol & 0x8000) ? (symbol & 15) : 0));
if (symbol & 0x8000)
{
get_bits_no_markers((symbol >> 8) & 31);
extra_bits = symbol >> 16;
}
else
{
int code_size = (symbol >> 8) & 31;
int num_extra_bits = symbol & 0xF;
int bits = code_size + num_extra_bits;
if (bits <= (m_bits_left + 16))
extra_bits = get_bits_no_markers(bits) & ((1 << num_extra_bits) - 1);
else
{
get_bits_no_markers(code_size);
extra_bits = get_bits_no_markers(num_extra_bits);
}
}
symbol &= 0xFF;
}
return symbol;
}
// Tables and macro used to fully decode the DPCM differences.
static const int s_extend_test[16] = { 0, 0x0001, 0x0002, 0x0004, 0x0008, 0x0010, 0x0020, 0x0040, 0x0080, 0x0100, 0x0200, 0x0400, 0x0800, 0x1000, 0x2000, 0x4000 };
static const int s_extend_offset[16] = { 0, ((-1)<<1) + 1, ((-1)<<2) + 1, ((-1)<<3) + 1, ((-1)<<4) + 1, ((-1)<<5) + 1, ((-1)<<6) + 1, ((-1)<<7) + 1, ((-1)<<8) + 1, ((-1)<<9) + 1, ((-1)<<10) + 1, ((-1)<<11) + 1, ((-1)<<12) + 1, ((-1)<<13) + 1, ((-1)<<14) + 1, ((-1)<<15) + 1 };
static const int s_extend_mask[] = { 0, (1<<0), (1<<1), (1<<2), (1<<3), (1<<4), (1<<5), (1<<6), (1<<7), (1<<8), (1<<9), (1<<10), (1<<11), (1<<12), (1<<13), (1<<14), (1<<15), (1<<16) };
// The logical AND's in this macro are to shut up static code analysis (aren't really necessary - couldn't find another way to do this)
#define JPGD_HUFF_EXTEND(x, s) (((x) < s_extend_test[s & 15]) ? ((x) + s_extend_offset[s & 15]) : (x))
// Clamps a value between 0-255.
inline uint8 jpeg_decoder::clamp(int i)
{
if (static_cast<uint>(i) > 255)
i = (((~i) >> 31) & 0xFF);
return static_cast<uint8>(i);
}
namespace DCT_Upsample
{
struct Matrix44
{
typedef int Element_Type;
enum { NUM_ROWS = 4, NUM_COLS = 4 };
Element_Type v[NUM_ROWS][NUM_COLS];
inline int rows() const { return NUM_ROWS; }
inline int cols() const { return NUM_COLS; }
inline const Element_Type & at(int r, int c) const { return v[r][c]; }
inline Element_Type & at(int r, int c) { return v[r][c]; }
inline Matrix44() { }
inline Matrix44& operator += (const Matrix44& a)
{
for (int r = 0; r < NUM_ROWS; r++)
{
at(r, 0) += a.at(r, 0);
at(r, 1) += a.at(r, 1);
at(r, 2) += a.at(r, 2);
at(r, 3) += a.at(r, 3);
}
return *this;
}
inline Matrix44& operator -= (const Matrix44& a)
{
for (int r = 0; r < NUM_ROWS; r++)
{
at(r, 0) -= a.at(r, 0);
at(r, 1) -= a.at(r, 1);
at(r, 2) -= a.at(r, 2);
at(r, 3) -= a.at(r, 3);
}
return *this;
}
friend inline Matrix44 operator + (const Matrix44& a, const Matrix44& b)
{
Matrix44 ret;
for (int r = 0; r < NUM_ROWS; r++)
{
ret.at(r, 0) = a.at(r, 0) + b.at(r, 0);
ret.at(r, 1) = a.at(r, 1) + b.at(r, 1);
ret.at(r, 2) = a.at(r, 2) + b.at(r, 2);
ret.at(r, 3) = a.at(r, 3) + b.at(r, 3);
}
return ret;
}
friend inline Matrix44 operator - (const Matrix44& a, const Matrix44& b)
{
Matrix44 ret;
for (int r = 0; r < NUM_ROWS; r++)
{
ret.at(r, 0) = a.at(r, 0) - b.at(r, 0);
ret.at(r, 1) = a.at(r, 1) - b.at(r, 1);
ret.at(r, 2) = a.at(r, 2) - b.at(r, 2);
ret.at(r, 3) = a.at(r, 3) - b.at(r, 3);
}
return ret;
}
static inline void add_and_store(jpgd_block_t* pDst, const Matrix44& a, const Matrix44& b)
{
for (int r = 0; r < 4; r++)
{
pDst[0*8 + r] = static_cast<jpgd_block_t>(a.at(r, 0) + b.at(r, 0));
pDst[1*8 + r] = static_cast<jpgd_block_t>(a.at(r, 1) + b.at(r, 1));
pDst[2*8 + r] = static_cast<jpgd_block_t>(a.at(r, 2) + b.at(r, 2));
pDst[3*8 + r] = static_cast<jpgd_block_t>(a.at(r, 3) + b.at(r, 3));
}
}
static inline void sub_and_store(jpgd_block_t* pDst, const Matrix44& a, const Matrix44& b)
{
for (int r = 0; r < 4; r++)
{
pDst[0*8 + r] = static_cast<jpgd_block_t>(a.at(r, 0) - b.at(r, 0));
pDst[1*8 + r] = static_cast<jpgd_block_t>(a.at(r, 1) - b.at(r, 1));
pDst[2*8 + r] = static_cast<jpgd_block_t>(a.at(r, 2) - b.at(r, 2));
pDst[3*8 + r] = static_cast<jpgd_block_t>(a.at(r, 3) - b.at(r, 3));
}
}
};
const int FRACT_BITS = 10;
const int SCALE = 1 << FRACT_BITS;
typedef int Temp_Type;
#define D(i) (((i) + (SCALE >> 1)) >> FRACT_BITS)
#define F(i) ((int)((i) * SCALE + .5f))
// Any decent C++ compiler will optimize this at compile time to a 0, or an array access.
#define AT(c, r) ((((c)>=NUM_COLS)||((r)>=NUM_ROWS)) ? 0 : pSrc[(c)+(r)*8])
// NUM_ROWS/NUM_COLS = # of non-zero rows/cols in input matrix
template<int NUM_ROWS, int NUM_COLS>
struct P_Q
{
static void calc(Matrix44& P, Matrix44& Q, const jpgd_block_t* pSrc)
{
// 4x8 = 4x8 times 8x8, matrix 0 is constant
const Temp_Type X000 = AT(0, 0);
const Temp_Type X001 = AT(0, 1);
const Temp_Type X002 = AT(0, 2);
const Temp_Type X003 = AT(0, 3);
const Temp_Type X004 = AT(0, 4);
const Temp_Type X005 = AT(0, 5);
const Temp_Type X006 = AT(0, 6);
const Temp_Type X007 = AT(0, 7);
const Temp_Type X010 = D(F(0.415735f) * AT(1, 0) + F(0.791065f) * AT(3, 0) + F(-0.352443f) * AT(5, 0) + F(0.277785f) * AT(7, 0));
const Temp_Type X011 = D(F(0.415735f) * AT(1, 1) + F(0.791065f) * AT(3, 1) + F(-0.352443f) * AT(5, 1) + F(0.277785f) * AT(7, 1));
const Temp_Type X012 = D(F(0.415735f) * AT(1, 2) + F(0.791065f) * AT(3, 2) + F(-0.352443f) * AT(5, 2) + F(0.277785f) * AT(7, 2));
const Temp_Type X013 = D(F(0.415735f) * AT(1, 3) + F(0.791065f) * AT(3, 3) + F(-0.352443f) * AT(5, 3) + F(0.277785f) * AT(7, 3));
const Temp_Type X014 = D(F(0.415735f) * AT(1, 4) + F(0.791065f) * AT(3, 4) + F(-0.352443f) * AT(5, 4) + F(0.277785f) * AT(7, 4));
const Temp_Type X015 = D(F(0.415735f) * AT(1, 5) + F(0.791065f) * AT(3, 5) + F(-0.352443f) * AT(5, 5) + F(0.277785f) * AT(7, 5));
const Temp_Type X016 = D(F(0.415735f) * AT(1, 6) + F(0.791065f) * AT(3, 6) + F(-0.352443f) * AT(5, 6) + F(0.277785f) * AT(7, 6));
const Temp_Type X017 = D(F(0.415735f) * AT(1, 7) + F(0.791065f) * AT(3, 7) + F(-0.352443f) * AT(5, 7) + F(0.277785f) * AT(7, 7));
const Temp_Type X020 = AT(4, 0);
const Temp_Type X021 = AT(4, 1);
const Temp_Type X022 = AT(4, 2);
const Temp_Type X023 = AT(4, 3);
const Temp_Type X024 = AT(4, 4);
const Temp_Type X025 = AT(4, 5);
const Temp_Type X026 = AT(4, 6);
const Temp_Type X027 = AT(4, 7);
const Temp_Type X030 = D(F(0.022887f) * AT(1, 0) + F(-0.097545f) * AT(3, 0) + F(0.490393f) * AT(5, 0) + F(0.865723f) * AT(7, 0));
const Temp_Type X031 = D(F(0.022887f) * AT(1, 1) + F(-0.097545f) * AT(3, 1) + F(0.490393f) * AT(5, 1) + F(0.865723f) * AT(7, 1));
const Temp_Type X032 = D(F(0.022887f) * AT(1, 2) + F(-0.097545f) * AT(3, 2) + F(0.490393f) * AT(5, 2) + F(0.865723f) * AT(7, 2));
const Temp_Type X033 = D(F(0.022887f) * AT(1, 3) + F(-0.097545f) * AT(3, 3) + F(0.490393f) * AT(5, 3) + F(0.865723f) * AT(7, 3));
const Temp_Type X034 = D(F(0.022887f) * AT(1, 4) + F(-0.097545f) * AT(3, 4) + F(0.490393f) * AT(5, 4) + F(0.865723f) * AT(7, 4));
const Temp_Type X035 = D(F(0.022887f) * AT(1, 5) + F(-0.097545f) * AT(3, 5) + F(0.490393f) * AT(5, 5) + F(0.865723f) * AT(7, 5));
const Temp_Type X036 = D(F(0.022887f) * AT(1, 6) + F(-0.097545f) * AT(3, 6) + F(0.490393f) * AT(5, 6) + F(0.865723f) * AT(7, 6));
const Temp_Type X037 = D(F(0.022887f) * AT(1, 7) + F(-0.097545f) * AT(3, 7) + F(0.490393f) * AT(5, 7) + F(0.865723f) * AT(7, 7));
// 4x4 = 4x8 times 8x4, matrix 1 is constant
P.at(0, 0) = X000;
P.at(0, 1) = D(X001 * F(0.415735f) + X003 * F(0.791065f) + X005 * F(-0.352443f) + X007 * F(0.277785f));
P.at(0, 2) = X004;
P.at(0, 3) = D(X001 * F(0.022887f) + X003 * F(-0.097545f) + X005 * F(0.490393f) + X007 * F(0.865723f));
P.at(1, 0) = X010;
P.at(1, 1) = D(X011 * F(0.415735f) + X013 * F(0.791065f) + X015 * F(-0.352443f) + X017 * F(0.277785f));
P.at(1, 2) = X014;
P.at(1, 3) = D(X011 * F(0.022887f) + X013 * F(-0.097545f) + X015 * F(0.490393f) + X017 * F(0.865723f));
P.at(2, 0) = X020;
P.at(2, 1) = D(X021 * F(0.415735f) + X023 * F(0.791065f) + X025 * F(-0.352443f) + X027 * F(0.277785f));
P.at(2, 2) = X024;
P.at(2, 3) = D(X021 * F(0.022887f) + X023 * F(-0.097545f) + X025 * F(0.490393f) + X027 * F(0.865723f));
P.at(3, 0) = X030;
P.at(3, 1) = D(X031 * F(0.415735f) + X033 * F(0.791065f) + X035 * F(-0.352443f) + X037 * F(0.277785f));
P.at(3, 2) = X034;
P.at(3, 3) = D(X031 * F(0.022887f) + X033 * F(-0.097545f) + X035 * F(0.490393f) + X037 * F(0.865723f));
// 40 muls 24 adds
// 4x4 = 4x8 times 8x4, matrix 1 is constant
Q.at(0, 0) = D(X001 * F(0.906127f) + X003 * F(-0.318190f) + X005 * F(0.212608f) + X007 * F(-0.180240f));
Q.at(0, 1) = X002;
Q.at(0, 2) = D(X001 * F(-0.074658f) + X003 * F(0.513280f) + X005 * F(0.768178f) + X007 * F(-0.375330f));
Q.at(0, 3) = X006;
Q.at(1, 0) = D(X011 * F(0.906127f) + X013 * F(-0.318190f) + X015 * F(0.212608f) + X017 * F(-0.180240f));
Q.at(1, 1) = X012;
Q.at(1, 2) = D(X011 * F(-0.074658f) + X013 * F(0.513280f) + X015 * F(0.768178f) + X017 * F(-0.375330f));
Q.at(1, 3) = X016;
Q.at(2, 0) = D(X021 * F(0.906127f) + X023 * F(-0.318190f) + X025 * F(0.212608f) + X027 * F(-0.180240f));
Q.at(2, 1) = X022;
Q.at(2, 2) = D(X021 * F(-0.074658f) + X023 * F(0.513280f) + X025 * F(0.768178f) + X027 * F(-0.375330f));
Q.at(2, 3) = X026;
Q.at(3, 0) = D(X031 * F(0.906127f) + X033 * F(-0.318190f) + X035 * F(0.212608f) + X037 * F(-0.180240f));
Q.at(3, 1) = X032;
Q.at(3, 2) = D(X031 * F(-0.074658f) + X033 * F(0.513280f) + X035 * F(0.768178f) + X037 * F(-0.375330f));
Q.at(3, 3) = X036;
// 40 muls 24 adds
}
};
template<int NUM_ROWS, int NUM_COLS>
struct R_S
{
static void calc(Matrix44& R, Matrix44& S, const jpgd_block_t* pSrc)
{
// 4x8 = 4x8 times 8x8, matrix 0 is constant
const Temp_Type X100 = D(F(0.906127f) * AT(1, 0) + F(-0.318190f) * AT(3, 0) + F(0.212608f) * AT(5, 0) + F(-0.180240f) * AT(7, 0));
const Temp_Type X101 = D(F(0.906127f) * AT(1, 1) + F(-0.318190f) * AT(3, 1) + F(0.212608f) * AT(5, 1) + F(-0.180240f) * AT(7, 1));
const Temp_Type X102 = D(F(0.906127f) * AT(1, 2) + F(-0.318190f) * AT(3, 2) + F(0.212608f) * AT(5, 2) + F(-0.180240f) * AT(7, 2));
const Temp_Type X103 = D(F(0.906127f) * AT(1, 3) + F(-0.318190f) * AT(3, 3) + F(0.212608f) * AT(5, 3) + F(-0.180240f) * AT(7, 3));
const Temp_Type X104 = D(F(0.906127f) * AT(1, 4) + F(-0.318190f) * AT(3, 4) + F(0.212608f) * AT(5, 4) + F(-0.180240f) * AT(7, 4));
const Temp_Type X105 = D(F(0.906127f) * AT(1, 5) + F(-0.318190f) * AT(3, 5) + F(0.212608f) * AT(5, 5) + F(-0.180240f) * AT(7, 5));
const Temp_Type X106 = D(F(0.906127f) * AT(1, 6) + F(-0.318190f) * AT(3, 6) + F(0.212608f) * AT(5, 6) + F(-0.180240f) * AT(7, 6));
const Temp_Type X107 = D(F(0.906127f) * AT(1, 7) + F(-0.318190f) * AT(3, 7) + F(0.212608f) * AT(5, 7) + F(-0.180240f) * AT(7, 7));
const Temp_Type X110 = AT(2, 0);
const Temp_Type X111 = AT(2, 1);
const Temp_Type X112 = AT(2, 2);
const Temp_Type X113 = AT(2, 3);
const Temp_Type X114 = AT(2, 4);
const Temp_Type X115 = AT(2, 5);
const Temp_Type X116 = AT(2, 6);
const Temp_Type X117 = AT(2, 7);
const Temp_Type X120 = D(F(-0.074658f) * AT(1, 0) + F(0.513280f) * AT(3, 0) + F(0.768178f) * AT(5, 0) + F(-0.375330f) * AT(7, 0));
const Temp_Type X121 = D(F(-0.074658f) * AT(1, 1) + F(0.513280f) * AT(3, 1) + F(0.768178f) * AT(5, 1) + F(-0.375330f) * AT(7, 1));
const Temp_Type X122 = D(F(-0.074658f) * AT(1, 2) + F(0.513280f) * AT(3, 2) + F(0.768178f) * AT(5, 2) + F(-0.375330f) * AT(7, 2));
const Temp_Type X123 = D(F(-0.074658f) * AT(1, 3) + F(0.513280f) * AT(3, 3) + F(0.768178f) * AT(5, 3) + F(-0.375330f) * AT(7, 3));
const Temp_Type X124 = D(F(-0.074658f) * AT(1, 4) + F(0.513280f) * AT(3, 4) + F(0.768178f) * AT(5, 4) + F(-0.375330f) * AT(7, 4));
const Temp_Type X125 = D(F(-0.074658f) * AT(1, 5) + F(0.513280f) * AT(3, 5) + F(0.768178f) * AT(5, 5) + F(-0.375330f) * AT(7, 5));
const Temp_Type X126 = D(F(-0.074658f) * AT(1, 6) + F(0.513280f) * AT(3, 6) + F(0.768178f) * AT(5, 6) + F(-0.375330f) * AT(7, 6));
const Temp_Type X127 = D(F(-0.074658f) * AT(1, 7) + F(0.513280f) * AT(3, 7) + F(0.768178f) * AT(5, 7) + F(-0.375330f) * AT(7, 7));
const Temp_Type X130 = AT(6, 0);
const Temp_Type X131 = AT(6, 1);
const Temp_Type X132 = AT(6, 2);
const Temp_Type X133 = AT(6, 3);
const Temp_Type X134 = AT(6, 4);
const Temp_Type X135 = AT(6, 5);
const Temp_Type X136 = AT(6, 6);
const Temp_Type X137 = AT(6, 7);
// 80 muls 48 adds
// 4x4 = 4x8 times 8x4, matrix 1 is constant
R.at(0, 0) = X100;
R.at(0, 1) = D(X101 * F(0.415735f) + X103 * F(0.791065f) + X105 * F(-0.352443f) + X107 * F(0.277785f));
R.at(0, 2) = X104;
R.at(0, 3) = D(X101 * F(0.022887f) + X103 * F(-0.097545f) + X105 * F(0.490393f) + X107 * F(0.865723f));
R.at(1, 0) = X110;
R.at(1, 1) = D(X111 * F(0.415735f) + X113 * F(0.791065f) + X115 * F(-0.352443f) + X117 * F(0.277785f));
R.at(1, 2) = X114;
R.at(1, 3) = D(X111 * F(0.022887f) + X113 * F(-0.097545f) + X115 * F(0.490393f) + X117 * F(0.865723f));
R.at(2, 0) = X120;
R.at(2, 1) = D(X121 * F(0.415735f) + X123 * F(0.791065f) + X125 * F(-0.352443f) + X127 * F(0.277785f));
R.at(2, 2) = X124;
R.at(2, 3) = D(X121 * F(0.022887f) + X123 * F(-0.097545f) + X125 * F(0.490393f) + X127 * F(0.865723f));
R.at(3, 0) = X130;
R.at(3, 1) = D(X131 * F(0.415735f) + X133 * F(0.791065f) + X135 * F(-0.352443f) + X137 * F(0.277785f));
R.at(3, 2) = X134;
R.at(3, 3) = D(X131 * F(0.022887f) + X133 * F(-0.097545f) + X135 * F(0.490393f) + X137 * F(0.865723f));
// 40 muls 24 adds
// 4x4 = 4x8 times 8x4, matrix 1 is constant
S.at(0, 0) = D(X101 * F(0.906127f) + X103 * F(-0.318190f) + X105 * F(0.212608f) + X107 * F(-0.180240f));
S.at(0, 1) = X102;
S.at(0, 2) = D(X101 * F(-0.074658f) + X103 * F(0.513280f) + X105 * F(0.768178f) + X107 * F(-0.375330f));
S.at(0, 3) = X106;
S.at(1, 0) = D(X111 * F(0.906127f) + X113 * F(-0.318190f) + X115 * F(0.212608f) + X117 * F(-0.180240f));
S.at(1, 1) = X112;
S.at(1, 2) = D(X111 * F(-0.074658f) + X113 * F(0.513280f) + X115 * F(0.768178f) + X117 * F(-0.375330f));
S.at(1, 3) = X116;
S.at(2, 0) = D(X121 * F(0.906127f) + X123 * F(-0.318190f) + X125 * F(0.212608f) + X127 * F(-0.180240f));
S.at(2, 1) = X122;
S.at(2, 2) = D(X121 * F(-0.074658f) + X123 * F(0.513280f) + X125 * F(0.768178f) + X127 * F(-0.375330f));
S.at(2, 3) = X126;
S.at(3, 0) = D(X131 * F(0.906127f) + X133 * F(-0.318190f) + X135 * F(0.212608f) + X137 * F(-0.180240f));
S.at(3, 1) = X132;
S.at(3, 2) = D(X131 * F(-0.074658f) + X133 * F(0.513280f) + X135 * F(0.768178f) + X137 * F(-0.375330f));
S.at(3, 3) = X136;
// 40 muls 24 adds
}
};
} // end namespace DCT_Upsample
// Unconditionally frees all allocated m_blocks.
void jpeg_decoder::free_all_blocks()
{
m_pStream = NULL;
for (mem_block *b = m_pMem_blocks; b; )
{
mem_block *n = b->m_pNext;
jpgd_free(b);
b = n;
}
m_pMem_blocks = NULL;
}
// This method handles all errors. It will never return.
// It could easily be changed to use C++ exceptions.
JPGD_NORETURN void jpeg_decoder::stop_decoding(jpgd_status status)
{
m_error_code = status;
free_all_blocks();
longjmp(m_jmp_state, status);
}
void *jpeg_decoder::alloc(size_t nSize, bool zero)
{
nSize = (JPGD_MAX(nSize, 1) + 3) & ~3;
char *rv = NULL;
for (mem_block *b = m_pMem_blocks; b; b = b->m_pNext)
{
if ((b->m_used_count + nSize) <= b->m_size)
{
rv = b->m_data + b->m_used_count;
b->m_used_count += nSize;
break;
}
}
if (!rv)
{
int capacity = JPGD_MAX(32768 - 256, (nSize + 2047) & ~2047);
mem_block *b = (mem_block*)jpgd_malloc(sizeof(mem_block) + capacity);
if (!b) { stop_decoding(JPGD_NOTENOUGHMEM); }
b->m_pNext = m_pMem_blocks; m_pMem_blocks = b;
b->m_used_count = nSize;
b->m_size = capacity;
rv = b->m_data;
}
if (zero) memset(rv, 0, nSize);
return rv;
}
void jpeg_decoder::word_clear(void *p, uint16 c, uint n)
{
uint8 *pD = (uint8*)p;
const uint8 l = c & 0xFF, h = (c >> 8) & 0xFF;
while (n)
{
pD[0] = l; pD[1] = h; pD += 2;
n--;
}
}
// Refill the input buffer.
// This method will sit in a loop until (A) the buffer is full or (B)
// the stream's read() method reports and end of file condition.
void jpeg_decoder::prep_in_buffer()
{
m_in_buf_left = 0;
m_pIn_buf_ofs = m_in_buf;
if (m_eof_flag)
return;
do
{
int bytes_read = m_pStream->read(m_in_buf + m_in_buf_left, JPGD_IN_BUF_SIZE - m_in_buf_left, &m_eof_flag);
if (bytes_read == -1)
stop_decoding(JPGD_STREAM_READ);
m_in_buf_left += bytes_read;
} while ((m_in_buf_left < JPGD_IN_BUF_SIZE) && (!m_eof_flag));
m_total_bytes_read += m_in_buf_left;
// Pad the end of the block with M_EOI (prevents the decompressor from going off the rails if the stream is invalid).
// (This dates way back to when this decompressor was written in C/asm, and the all-asm Huffman decoder did some fancy things to increase perf.)
word_clear(m_pIn_buf_ofs + m_in_buf_left, 0xD9FF, 64);
}
// Read a Huffman code table.
void jpeg_decoder::read_dht_marker()
{
int i, index, count;
uint8 huff_num[17];
uint8 huff_val[256];
uint num_left = get_bits(16);
if (num_left < 2)
stop_decoding(JPGD_BAD_DHT_MARKER);
num_left -= 2;
while (num_left)
{
index = get_bits(8);
huff_num[0] = 0;
count = 0;
for (i = 1; i <= 16; i++)
{
huff_num[i] = static_cast<uint8>(get_bits(8));
count += huff_num[i];
}
if (count > 255)
stop_decoding(JPGD_BAD_DHT_COUNTS);
for (i = 0; i < count; i++)
huff_val[i] = static_cast<uint8>(get_bits(8));
i = 1 + 16 + count;
if (num_left < (uint)i)
stop_decoding(JPGD_BAD_DHT_MARKER);
num_left -= i;
if ((index & 0x10) > 0x10)
stop_decoding(JPGD_BAD_DHT_INDEX);
index = (index & 0x0F) + ((index & 0x10) >> 4) * (JPGD_MAX_HUFF_TABLES >> 1);
if (index >= JPGD_MAX_HUFF_TABLES)
stop_decoding(JPGD_BAD_DHT_INDEX);
if (!m_huff_num[index])
m_huff_num[index] = (uint8 *)alloc(17);
if (!m_huff_val[index])
m_huff_val[index] = (uint8 *)alloc(256);
m_huff_ac[index] = (index & 0x10) != 0;
memcpy(m_huff_num[index], huff_num, 17);
memcpy(m_huff_val[index], huff_val, 256);
}
}
// Read a quantization table.
void jpeg_decoder::read_dqt_marker()
{
int n, i, prec;
uint num_left;
uint temp;
num_left = get_bits(16);
if (num_left < 2)
stop_decoding(JPGD_BAD_DQT_MARKER);