diff options
Diffstat (limited to 'jpeg/jfdctint.c')
| -rw-r--r-- | jpeg/jfdctint.c | 116 |
1 files changed, 61 insertions, 55 deletions
diff --git a/jpeg/jfdctint.c b/jpeg/jfdctint.c index 7ed42e5db..05df4750b 100644 --- a/jpeg/jfdctint.c +++ b/jpeg/jfdctint.c @@ -2,7 +2,7 @@ * jfdctint.c * * Copyright (C) 1991-1996, Thomas G. Lane. - * Modification developed 2003-2015 by Guido Vollbeding. + * Modification developed 2003-2018 by Guido Vollbeding. * This file is part of the Independent JPEG Group's software. * For conditions of distribution and use, see the accompanying README file. * @@ -3261,78 +3261,84 @@ jpeg_fdct_6x3 (DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col) GLOBAL(void) jpeg_fdct_4x2 (DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col) { - INT32 tmp0, tmp1; - INT32 tmp10, tmp11; - DCTELEM *dataptr; + DCTELEM tmp0, tmp2, tmp10, tmp12, tmp4, tmp5; + INT32 tmp1, tmp3, tmp11, tmp13; + INT32 z1, z2, z3; JSAMPROW elemptr; - int ctr; SHIFT_TEMPS /* Pre-zero output coefficient block. */ MEMZERO(data, SIZEOF(DCTELEM) * DCTSIZE2); /* Pass 1: process rows. - * Note results are scaled up by sqrt(8) compared to a true DCT; - * furthermore, we scale the results by 2**PASS1_BITS. - * We must also scale the output by (8/4)*(8/2) = 2**3, which we add here. + * Note results are scaled up by sqrt(8) compared to a true DCT. * 4-point FDCT kernel, * cK represents sqrt(2) * cos(K*pi/16) [refers to 8-point FDCT]. */ - dataptr = data; - for (ctr = 0; ctr < 2; ctr++) { - elemptr = sample_data[ctr] + start_col; + /* Row 0 */ + elemptr = sample_data[0] + start_col; - /* Even part */ + /* Even part */ - tmp0 = GETJSAMPLE(elemptr[0]) + GETJSAMPLE(elemptr[3]); - tmp1 = GETJSAMPLE(elemptr[1]) + GETJSAMPLE(elemptr[2]); + tmp4 = GETJSAMPLE(elemptr[0]) + GETJSAMPLE(elemptr[3]); + tmp5 = GETJSAMPLE(elemptr[1]) + GETJSAMPLE(elemptr[2]); - tmp10 = GETJSAMPLE(elemptr[0]) - GETJSAMPLE(elemptr[3]); - tmp11 = GETJSAMPLE(elemptr[1]) - GETJSAMPLE(elemptr[2]); + tmp0 = tmp4 + tmp5; + tmp2 = tmp4 - tmp5; - /* Apply unsigned->signed conversion. */ - dataptr[0] = (DCTELEM) - ((tmp0 + tmp1 - 4 * CENTERJSAMPLE) << (PASS1_BITS+3)); - dataptr[2] = (DCTELEM) ((tmp0 - tmp1) << (PASS1_BITS+3)); + /* Odd part */ - /* Odd part */ + z2 = GETJSAMPLE(elemptr[0]) - GETJSAMPLE(elemptr[3]); + z3 = GETJSAMPLE(elemptr[1]) - GETJSAMPLE(elemptr[2]); - tmp0 = MULTIPLY(tmp10 + tmp11, FIX_0_541196100); /* c6 */ - /* Add fudge factor here for final descale. */ - tmp0 += ONE << (CONST_BITS-PASS1_BITS-4); + z1 = MULTIPLY(z2 + z3, FIX_0_541196100); /* c6 */ + /* Add fudge factor here for final descale. */ + z1 += ONE << (CONST_BITS-3-1); + tmp1 = z1 + MULTIPLY(z2, FIX_0_765366865); /* c2-c6 */ + tmp3 = z1 - MULTIPLY(z3, FIX_1_847759065); /* c2+c6 */ - dataptr[1] = (DCTELEM) - RIGHT_SHIFT(tmp0 + MULTIPLY(tmp10, FIX_0_765366865), /* c2-c6 */ - CONST_BITS-PASS1_BITS-3); - dataptr[3] = (DCTELEM) - RIGHT_SHIFT(tmp0 - MULTIPLY(tmp11, FIX_1_847759065), /* c2+c6 */ - CONST_BITS-PASS1_BITS-3); + /* Row 1 */ + elemptr = sample_data[1] + start_col; - dataptr += DCTSIZE; /* advance pointer to next row */ - } + /* Even part */ - /* Pass 2: process columns. - * We remove the PASS1_BITS scaling, but leave the results scaled up - * by an overall factor of 8. - */ + tmp4 = GETJSAMPLE(elemptr[0]) + GETJSAMPLE(elemptr[3]); + tmp5 = GETJSAMPLE(elemptr[1]) + GETJSAMPLE(elemptr[2]); - dataptr = data; - for (ctr = 0; ctr < 4; ctr++) { - /* Even part */ + tmp10 = tmp4 + tmp5; + tmp12 = tmp4 - tmp5; - /* Add fudge factor here for final descale. */ - tmp0 = dataptr[DCTSIZE*0] + (ONE << (PASS1_BITS-1)); - tmp1 = dataptr[DCTSIZE*1]; + /* Odd part */ - dataptr[DCTSIZE*0] = (DCTELEM) RIGHT_SHIFT(tmp0 + tmp1, PASS1_BITS); + z2 = GETJSAMPLE(elemptr[0]) - GETJSAMPLE(elemptr[3]); + z3 = GETJSAMPLE(elemptr[1]) - GETJSAMPLE(elemptr[2]); - /* Odd part */ + z1 = MULTIPLY(z2 + z3, FIX_0_541196100); /* c6 */ + tmp11 = z1 + MULTIPLY(z2, FIX_0_765366865); /* c2-c6 */ + tmp13 = z1 - MULTIPLY(z3, FIX_1_847759065); /* c2+c6 */ - dataptr[DCTSIZE*1] = (DCTELEM) RIGHT_SHIFT(tmp0 - tmp1, PASS1_BITS); + /* Pass 2: process columns. + * We leave the results scaled up by an overall factor of 8. + * We must also scale the output by (8/4)*(8/2) = 2**3. + */ - dataptr++; /* advance pointer to next column */ - } + /* Column 0 */ + /* Apply unsigned->signed conversion. */ + data[DCTSIZE*0] = (tmp0 + tmp10 - 8 * CENTERJSAMPLE) << 3; + data[DCTSIZE*1] = (tmp0 - tmp10) << 3; + + /* Column 1 */ + data[DCTSIZE*0+1] = (DCTELEM) RIGHT_SHIFT(tmp1 + tmp11, CONST_BITS-3); + data[DCTSIZE*1+1] = (DCTELEM) RIGHT_SHIFT(tmp1 - tmp11, CONST_BITS-3); + + /* Column 2 */ + data[DCTSIZE*0+2] = (tmp2 + tmp12) << 3; + data[DCTSIZE*1+2] = (tmp2 - tmp12) << 3; + + /* Column 3 */ + data[DCTSIZE*0+3] = (DCTELEM) RIGHT_SHIFT(tmp3 + tmp13, CONST_BITS-3); + data[DCTSIZE*1+3] = (DCTELEM) RIGHT_SHIFT(tmp3 - tmp13, CONST_BITS-3); } @@ -4312,7 +4318,6 @@ jpeg_fdct_2x4 (DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col) /* Pass 1: process rows. * Note results are scaled up by sqrt(8) compared to a true DCT. - * We must also scale the output by (8/2)*(8/4) = 2**3, which we add here. */ dataptr = data; @@ -4325,17 +4330,18 @@ jpeg_fdct_2x4 (DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col) tmp1 = GETJSAMPLE(elemptr[1]); /* Apply unsigned->signed conversion. */ - dataptr[0] = (DCTELEM) ((tmp0 + tmp1 - 2 * CENTERJSAMPLE) << 3); + dataptr[0] = (DCTELEM) (tmp0 + tmp1 - 2 * CENTERJSAMPLE); /* Odd part */ - dataptr[1] = (DCTELEM) ((tmp0 - tmp1) << 3); + dataptr[1] = (DCTELEM) (tmp0 - tmp1); dataptr += DCTSIZE; /* advance pointer to next row */ } /* Pass 2: process columns. * We leave the results scaled up by an overall factor of 8. + * We must also scale the output by (8/2)*(8/4) = 2**3. * 4-point FDCT kernel, * cK represents sqrt(2) * cos(K*pi/16) [refers to 8-point FDCT]. */ @@ -4350,21 +4356,21 @@ jpeg_fdct_2x4 (DCTELEM * data, JSAMPARRAY sample_data, JDIMENSION start_col) tmp10 = dataptr[DCTSIZE*0] - dataptr[DCTSIZE*3]; tmp11 = dataptr[DCTSIZE*1] - dataptr[DCTSIZE*2]; - dataptr[DCTSIZE*0] = (DCTELEM) (tmp0 + tmp1); - dataptr[DCTSIZE*2] = (DCTELEM) (tmp0 - tmp1); + dataptr[DCTSIZE*0] = (DCTELEM) ((tmp0 + tmp1) << 3); + dataptr[DCTSIZE*2] = (DCTELEM) ((tmp0 - tmp1) << 3); /* Odd part */ tmp0 = MULTIPLY(tmp10 + tmp11, FIX_0_541196100); /* c6 */ /* Add fudge factor here for final descale. */ - tmp0 += ONE << (CONST_BITS-1); + tmp0 += ONE << (CONST_BITS-3-1); dataptr[DCTSIZE*1] = (DCTELEM) RIGHT_SHIFT(tmp0 + MULTIPLY(tmp10, FIX_0_765366865), /* c2-c6 */ - CONST_BITS); + CONST_BITS-3); dataptr[DCTSIZE*3] = (DCTELEM) RIGHT_SHIFT(tmp0 - MULTIPLY(tmp11, FIX_1_847759065), /* c2+c6 */ - CONST_BITS); + CONST_BITS-3); dataptr++; /* advance pointer to next column */ } |