📄 jrevdct.c
字号:
z3 += z5;
z4 += z5;
tmp0 += z1 + z3;
tmp1 = z2 + z4;
tmp2 += z2 + z3;
tmp3 += z1 + z4;
} else {
/* d1 == 0, d3 != 0, d5 == 0, d7 != 0 */
z3 = d7 + d3;
tmp0 = MULTIPLY(-d7, FIX_0_601344887);
z1 = MULTIPLY(-d7, FIX_0_899976223);
tmp2 = MULTIPLY(d3, FIX_0_509795579);
z2 = MULTIPLY(-d3, FIX_2_562915447);
z5 = MULTIPLY(z3, FIX_1_175875602);
z3 = MULTIPLY(-z3, FIX_0_785694958);
tmp0 += z3;
tmp1 = z2 + z5;
tmp2 += z3;
tmp3 = z1 + z5;
}
} else {
if (d1) {
/* d1 != 0, d3 == 0, d5 == 0, d7 != 0 */
z1 = d7 + d1;
z5 = MULTIPLY(z1, FIX_1_175875602);
z1 = MULTIPLY(z1, FIX_0_275899380);
z3 = MULTIPLY(-d7, FIX_1_961570560);
tmp0 = MULTIPLY(-d7, FIX_1_662939225);
z4 = MULTIPLY(-d1, FIX_0_390180644);
tmp3 = MULTIPLY(d1, FIX_1_111140466);
tmp0 += z1;
tmp1 = z4 + z5;
tmp2 = z3 + z5;
tmp3 += z1;
} else {
/* d1 == 0, d3 == 0, d5 == 0, d7 != 0 */
tmp0 = MULTIPLY(-d7, FIX_1_387039845);
tmp1 = MULTIPLY(d7, FIX_1_175875602);
tmp2 = MULTIPLY(-d7, FIX_0_785694958);
tmp3 = MULTIPLY(d7, FIX_0_275899380);
}
}
}
} else {
if (d5) {
if (d3) {
if (d1) {
/* d1 != 0, d3 != 0, d5 != 0, d7 == 0 */
z2 = d5 + d3;
z4 = d5 + d1;
z5 = MULTIPLY(d3 + z4, FIX_1_175875602);
tmp1 = MULTIPLY(d5, FIX_2_053119869);
tmp2 = MULTIPLY(d3, FIX_3_072711026);
tmp3 = MULTIPLY(d1, FIX_1_501321110);
z1 = MULTIPLY(-d1, FIX_0_899976223);
z2 = MULTIPLY(-z2, FIX_2_562915447);
z3 = MULTIPLY(-d3, FIX_1_961570560);
z4 = MULTIPLY(-z4, FIX_0_390180644);
z3 += z5;
z4 += z5;
tmp0 = z1 + z3;
tmp1 += z2 + z4;
tmp2 += z2 + z3;
tmp3 += z1 + z4;
} else {
/* d1 == 0, d3 != 0, d5 != 0, d7 == 0 */
z2 = d5 + d3;
z5 = MULTIPLY(z2, FIX_1_175875602);
tmp1 = MULTIPLY(d5, FIX_1_662939225);
z4 = MULTIPLY(-d5, FIX_0_390180644);
z2 = MULTIPLY(-z2, FIX_1_387039845);
tmp2 = MULTIPLY(d3, FIX_1_111140466);
z3 = MULTIPLY(-d3, FIX_1_961570560);
tmp0 = z3 + z5;
tmp1 += z2;
tmp2 += z2;
tmp3 = z4 + z5;
}
} else {
if (d1) {
/* d1 != 0, d3 == 0, d5 != 0, d7 == 0 */
z4 = d5 + d1;
z5 = MULTIPLY(z4, FIX_1_175875602);
z1 = MULTIPLY(-d1, FIX_0_899976223);
tmp3 = MULTIPLY(d1, FIX_0_601344887);
tmp1 = MULTIPLY(-d5, FIX_0_509795579);
z2 = MULTIPLY(-d5, FIX_2_562915447);
z4 = MULTIPLY(z4, FIX_0_785694958);
tmp0 = z1 + z5;
tmp1 += z4;
tmp2 = z2 + z5;
tmp3 += z4;
} else {
/* d1 == 0, d3 == 0, d5 != 0, d7 == 0 */
tmp0 = MULTIPLY(d5, FIX_1_175875602);
tmp1 = MULTIPLY(d5, FIX_0_275899380);
tmp2 = MULTIPLY(-d5, FIX_1_387039845);
tmp3 = MULTIPLY(d5, FIX_0_785694958);
}
}
} else {
if (d3) {
if (d1) {
/* d1 != 0, d3 != 0, d5 == 0, d7 == 0 */
z5 = d1 + d3;
tmp3 = MULTIPLY(d1, FIX_0_211164243);
tmp2 = MULTIPLY(-d3, FIX_1_451774981);
z1 = MULTIPLY(d1, FIX_1_061594337);
z2 = MULTIPLY(-d3, FIX_2_172734803);
z4 = MULTIPLY(z5, FIX_0_785694958);
z5 = MULTIPLY(z5, FIX_1_175875602);
tmp0 = z1 - z4;
tmp1 = z2 + z4;
tmp2 += z5;
tmp3 += z5;
} else {
/* d1 == 0, d3 != 0, d5 == 0, d7 == 0 */
tmp0 = MULTIPLY(-d3, FIX_0_785694958);
tmp1 = MULTIPLY(-d3, FIX_1_387039845);
tmp2 = MULTIPLY(-d3, FIX_0_275899380);
tmp3 = MULTIPLY(d3, FIX_1_175875602);
}
} else {
if (d1) {
/* d1 != 0, d3 == 0, d5 == 0, d7 == 0 */
tmp0 = MULTIPLY(d1, FIX_0_275899380);
tmp1 = MULTIPLY(d1, FIX_0_785694958);
tmp2 = MULTIPLY(d1, FIX_1_175875602);
tmp3 = MULTIPLY(d1, FIX_1_387039845);
} else {
/* d1 == 0, d3 == 0, d5 == 0, d7 == 0 */
tmp0 = tmp1 = tmp2 = tmp3 = 0;
}
}
}
}
/* Final output stage: inputs are tmp10..tmp13, tmp0..tmp3 */
dataptr[DCTSIZE*0] = (DCTELEM) DESCALE(tmp10 + tmp3,
CONST_BITS+PASS1_BITS+3);
dataptr[DCTSIZE*7] = (DCTELEM) DESCALE(tmp10 - tmp3,
CONST_BITS+PASS1_BITS+3);
dataptr[DCTSIZE*1] = (DCTELEM) DESCALE(tmp11 + tmp2,
CONST_BITS+PASS1_BITS+3);
dataptr[DCTSIZE*6] = (DCTELEM) DESCALE(tmp11 - tmp2,
CONST_BITS+PASS1_BITS+3);
dataptr[DCTSIZE*2] = (DCTELEM) DESCALE(tmp12 + tmp1,
CONST_BITS+PASS1_BITS+3);
dataptr[DCTSIZE*5] = (DCTELEM) DESCALE(tmp12 - tmp1,
CONST_BITS+PASS1_BITS+3);
dataptr[DCTSIZE*3] = (DCTELEM) DESCALE(tmp13 + tmp0,
CONST_BITS+PASS1_BITS+3);
dataptr[DCTSIZE*4] = (DCTELEM) DESCALE(tmp13 - tmp0,
CONST_BITS+PASS1_BITS+3);
dataptr++; /* advance pointer to next column */
}
}
#undef DCTSIZE
#define DCTSIZE 4
#define DCTSTRIDE 8
void j_rev_dct4(DCTBLOCK data)
{
int32_t tmp0, tmp1, tmp2, tmp3;
int32_t tmp10, tmp11, tmp12, tmp13;
int32_t z1;
int32_t d0, d2, d4, d6;
register DCTELEM *dataptr;
int rowctr;
/* Pass 1: process rows. */
/* Note results are scaled up by sqrt(8) compared to a true IDCT; */
/* furthermore, we scale the results by 2**PASS1_BITS. */
data[0] += 4;
dataptr = data;
for (rowctr = DCTSIZE-1; rowctr >= 0; rowctr--) {
/* Due to quantization, we will usually find that many of the input
* coefficients are zero, especially the AC terms. We can exploit this
* by short-circuiting the IDCT calculation for any row in which all
* the AC terms are zero. In that case each output is equal to the
* DC coefficient (with scale factor as needed).
* With typical images and quantization tables, half or more of the
* row DCT calculations can be simplified this way.
*/
register int *idataptr = (int*)dataptr;
d0 = dataptr[0];
d2 = dataptr[1];
d4 = dataptr[2];
d6 = dataptr[3];
if ((d2 | d4 | d6) == 0) {
/* AC terms all zero */
if (d0) {
/* Compute a 32 bit value to assign. */
DCTELEM dcval = (DCTELEM) (d0 << PASS1_BITS);
register int v = (dcval & 0xffff) | ((dcval << 16) & 0xffff0000);
idataptr[0] = v;
idataptr[1] = v;
}
dataptr += DCTSTRIDE; /* advance pointer to next row */
continue;
}
/* Even part: reverse the even part of the forward DCT. */
/* The rotator is sqrt(2)*c(-6). */
if (d6) {
if (d2) {
/* d0 != 0, d2 != 0, d4 != 0, d6 != 0 */
z1 = MULTIPLY(d2 + d6, FIX_0_541196100);
tmp2 = z1 + MULTIPLY(-d6, FIX_1_847759065);
tmp3 = z1 + MULTIPLY(d2, FIX_0_765366865);
tmp0 = (d0 + d4) << CONST_BITS;
tmp1 = (d0 - d4) << CONST_BITS;
tmp10 = tmp0 + tmp3;
tmp13 = tmp0 - tmp3;
tmp11 = tmp1 + tmp2;
tmp12 = tmp1 - tmp2;
} else {
/* d0 != 0, d2 == 0, d4 != 0, d6 != 0 */
tmp2 = MULTIPLY(-d6, FIX_1_306562965);
tmp3 = MULTIPLY(d6, FIX_0_541196100);
tmp0 = (d0 + d4) << CONST_BITS;
tmp1 = (d0 - d4) << CONST_BITS;
tmp10 = tmp0 + tmp3;
tmp13 = tmp0 - tmp3;
tmp11 = tmp1 + tmp2;
tmp12 = tmp1 - tmp2;
}
} else {
if (d2) {
/* d0 != 0, d2 != 0, d4 != 0, d6 == 0 */
tmp2 = MULTIPLY(d2, FIX_0_541196100);
tmp3 = MULTIPLY(d2, FIX_1_306562965);
tmp0 = (d0 + d4) << CONST_BITS;
tmp1 = (d0 - d4) << CONST_BITS;
tmp10 = tmp0 + tmp3;
tmp13 = tmp0 - tmp3;
tmp11 = tmp1 + tmp2;
tmp12 = tmp1 - tmp2;
} else {
/* d0 != 0, d2 == 0, d4 != 0, d6 == 0 */
tmp10 = tmp13 = (d0 + d4) << CONST_BITS;
tmp11 = tmp12 = (d0 - d4) << CONST_BITS;
}
}
/* Final output stage: inputs are tmp10..tmp13, tmp0..tmp3 */
dataptr[0] = (DCTELEM) DESCALE(tmp10, CONST_BITS-PASS1_BITS);
dataptr[1] = (DCTELEM) DESCALE(tmp11, CONST_BITS-PASS1_BITS);
dataptr[2] = (DCTELEM) DESCALE(tmp12, CONST_BITS-PASS1_BITS);
dataptr[3] = (DCTELEM) DESCALE(tmp13, CONST_BITS-PASS1_BITS);
dataptr += DCTSTRIDE; /* advance pointer to next row */
}
/* Pass 2: process columns. */
/* Note that we must descale the results by a factor of 8 == 2**3, */
/* and also undo the PASS1_BITS scaling. */
dataptr = data;
for (rowctr = DCTSIZE-1; rowctr >= 0; rowctr--) {
/* Columns of zeroes can be exploited in the same way as we did with rows.
* However, the row calculation has created many nonzero AC terms, so the
* simplification applies less often (typically 5% to 10% of the time).
* On machines with very fast multiplication, it's possible that the
* test takes more time than it's worth. In that case this section
* may be commented out.
*/
d0 = dataptr[DCTSTRIDE*0];
d2 = dataptr[DCTSTRIDE*1];
d4 = dataptr[DCTSTRIDE*2];
d6 = dataptr[DCTSTRIDE*3];
/* Even part: reverse the even part of the forward DCT. */
/* The rotator is sqrt(2)*c(-6). */
if (d6) {
if (d2) {
/* d0 != 0, d2 != 0, d4 != 0, d6 != 0 */
z1 = MULTIPLY(d2 + d6, FIX_0_541196100);
tmp2 = z1 + MULTIPLY(-d6, FIX_1_847759065);
tmp3 = z1 + MULTIPLY(d2, FIX_0_765366865);
tmp0 = (d0 + d4) << CONST_BITS;
tmp1 = (d0 - d4) << CONST_BITS;
tmp10 = tmp0 + tmp3;
tmp13 = tmp0 - tmp3;
tmp11 = tmp1 + tmp2;
tmp12 = tmp1 - tmp2;
} else {
/* d0 != 0, d2 == 0, d4 != 0, d6 != 0 */
tmp2 = MULTIPLY(-d6, FIX_1_306562965);
tmp3 = MULTIPLY(d6, FIX_0_541196100);
tmp0 = (d0 + d4) << CONST_BITS;
tmp1 = (d0 - d4) << CONST_BITS;
tmp10 = tmp0 + tmp3;
tmp13 = tmp0 - tmp3;
tmp11 = tmp1 + tmp2;
tmp12 = tmp1 - tmp2;
}
} else {
if (d2) {
/* d0 != 0, d2 != 0, d4 != 0, d6 == 0 */
tmp2 = MULTIPLY(d2, FIX_0_541196100);
tmp3 = MULTIPLY(d2, FIX_1_306562965);
tmp0 = (d0 + d4) << CONST_BITS;
tmp1 = (d0 - d4) << CONST_BITS;
tmp10 = tmp0 + tmp3;
tmp13 = tmp0 - tmp3;
tmp11 = tmp1 + tmp2;
tmp12 = tmp1 - tmp2;
} else {
/* d0 != 0, d2 == 0, d4 != 0, d6 == 0 */
tmp10 = tmp13 = (d0 + d4) << CONST_BITS;
tmp11 = tmp12 = (d0 - d4) << CONST_BITS;
}
}
/* Final output stage: inputs are tmp10..tmp13, tmp0..tmp3 */
dataptr[DCTSTRIDE*0] = tmp10 >> (CONST_BITS+PASS1_BITS+3);
dataptr[DCTSTRIDE*1] = tmp11 >> (CONST_BITS+PASS1_BITS+3);
dataptr[DCTSTRIDE*2] = tmp12 >> (CONST_BITS+PASS1_BITS+3);
dataptr[DCTSTRIDE*3] = tmp13 >> (CONST_BITS+PASS1_BITS+3);
dataptr++; /* advance pointer to next column */
}
}
void j_rev_dct2(DCTBLOCK data){
int d00, d01, d10, d11;
data[0] += 4;
d00 = data[0+0*DCTSTRIDE] + data[1+0*DCTSTRIDE];
d01 = data[0+0*DCTSTRIDE] - data[1+0*DCTSTRIDE];
d10 = data[0+1*DCTSTRIDE] + data[1+1*DCTSTRIDE];
d11 = data[0+1*DCTSTRIDE] - data[1+1*DCTSTRIDE];
data[0+0*DCTSTRIDE]= (d00 + d10)>>3;
data[1+0*DCTSTRIDE]= (d01 + d11)>>3;
data[0+1*DCTSTRIDE]= (d00 - d10)>>3;
data[1+1*DCTSTRIDE]= (d01 - d11)>>3;
}
void j_rev_dct1(DCTBLOCK data){
data[0] = (data[0] + 4)>>3;
}
#undef FIX
#undef CONST_BITS
⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -