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author | Michael Niedermayer <michaelni@gmx.at> | 2004-09-25 23:18:58 +0000 |
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committer | Michael Niedermayer <michaelni@gmx.at> | 2004-09-25 23:18:58 +0000 |
commit | 178fcca84883bdbff02d5ae8eb7825bf884b40d8 (patch) | |
tree | daf6d857ef63cf0ad688acdadf1091732507b965 /libavcodec/jrevdct.c | |
parent | bc133816c03b32d722fa43cfe1d199a273fc65b4 (diff) | |
download | ffmpeg-178fcca84883bdbff02d5ae8eb7825bf884b40d8.tar.gz |
1/2 resolution decoding
Originally committed as revision 3507 to svn://svn.ffmpeg.org/ffmpeg/trunk
Diffstat (limited to 'libavcodec/jrevdct.c')
-rw-r--r-- | libavcodec/jrevdct.c | 456 |
1 files changed, 456 insertions, 0 deletions
diff --git a/libavcodec/jrevdct.c b/libavcodec/jrevdct.c index 3bd78c1925..1c253fee39 100644 --- a/libavcodec/jrevdct.c +++ b/libavcodec/jrevdct.c @@ -1172,5 +1172,461 @@ void j_rev_dct(DCTBLOCK data) } } +#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. */ + + 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; + + /* WARNING: we do the same permutation as MMX idct to simplify the + video core */ + 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 (d4) { + if (d2) { + if (d0) { + /* 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 */ + z1 = MULTIPLY(d2 + d6, FIX_0_541196100); + tmp2 = z1 + MULTIPLY(-d6, FIX_1_847759065); + tmp3 = z1 + MULTIPLY(d2, FIX_0_765366865); + + tmp0 = d4 << CONST_BITS; + + tmp10 = tmp0 + tmp3; + tmp13 = tmp0 - tmp3; + tmp11 = tmp2 - tmp0; + tmp12 = -(tmp0 + tmp2); + } + } else { + if (d0) { + /* 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 { + /* d0 == 0, d2 == 0, d4 != 0, d6 != 0 */ + tmp2 = MULTIPLY(-d6, FIX_1_306562965); + tmp3 = MULTIPLY(d6, FIX_0_541196100); + + tmp0 = d4 << CONST_BITS; + + tmp10 = tmp0 + tmp3; + tmp13 = tmp0 - tmp3; + tmp11 = tmp2 - tmp0; + tmp12 = -(tmp0 + tmp2); + } + } + } else { + if (d2) { + if (d0) { + /* 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 << CONST_BITS; + + tmp10 = tmp0 + tmp3; + tmp13 = tmp0 - tmp3; + tmp11 = tmp0 + tmp2; + tmp12 = tmp0 - tmp2; + } else { + /* 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); + + tmp10 = tmp3; + tmp13 = -tmp3; + tmp11 = tmp2; + tmp12 = -tmp2; + } + } else { + if (d0) { + /* d0 != 0, d2 == 0, d4 == 0, d6 != 0 */ + tmp2 = MULTIPLY(-d6, FIX_1_306562965); + tmp3 = MULTIPLY(d6, FIX_0_541196100); + + tmp0 = d0 << CONST_BITS; + + tmp10 = tmp0 + tmp3; + tmp13 = tmp0 - tmp3; + tmp11 = tmp0 + tmp2; + tmp12 = tmp0 - tmp2; + } else { + /* d0 == 0, d2 == 0, d4 == 0, d6 != 0 */ + tmp2 = MULTIPLY(-d6, FIX_1_306562965); + tmp3 = MULTIPLY(d6, FIX_0_541196100); + + tmp10 = tmp3; + tmp13 = -tmp3; + tmp11 = tmp2; + tmp12 = -tmp2; + } + } + } + } else { + if (d4) { + if (d2) { + if (d0) { + /* 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 */ + tmp2 = MULTIPLY(d2, FIX_0_541196100); + tmp3 = MULTIPLY(d2, FIX_1_306562965); + + tmp0 = d4 << CONST_BITS; + + tmp10 = tmp0 + tmp3; + tmp13 = tmp0 - tmp3; + tmp11 = tmp2 - tmp0; + tmp12 = -(tmp0 + tmp2); + } + } else { + if (d0) { + /* d0 != 0, d2 == 0, d4 != 0, d6 == 0 */ + tmp10 = tmp13 = (d0 + d4) << CONST_BITS; + tmp11 = tmp12 = (d0 - d4) << CONST_BITS; + } else { + /* d0 == 0, d2 == 0, d4 != 0, d6 == 0 */ + tmp10 = tmp13 = d4 << CONST_BITS; + tmp11 = tmp12 = -tmp10; + } + } + } else { + if (d2) { + if (d0) { + /* d0 != 0, d2 != 0, d4 == 0, d6 == 0 */ + tmp2 = MULTIPLY(d2, FIX_0_541196100); + tmp3 = MULTIPLY(d2, FIX_1_306562965); + + tmp0 = d0 << CONST_BITS; + + tmp10 = tmp0 + tmp3; + tmp13 = tmp0 - tmp3; + tmp11 = tmp0 + tmp2; + tmp12 = tmp0 - tmp2; + } else { + /* d0 == 0, d2 != 0, d4 == 0, d6 == 0 */ + tmp2 = MULTIPLY(d2, FIX_0_541196100); + tmp3 = MULTIPLY(d2, FIX_1_306562965); + + tmp10 = tmp3; + tmp13 = -tmp3; + tmp11 = tmp2; + tmp12 = -tmp2; + } + } else { + if (d0) { + /* d0 != 0, d2 == 0, d4 == 0, d6 == 0 */ + tmp10 = tmp13 = tmp11 = tmp12 = d0 << CONST_BITS; + } else { + /* d0 == 0, d2 == 0, d4 == 0, d6 == 0 */ + tmp10 = tmp13 = tmp11 = tmp12 = 0; + } + } + } + } + + /* 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 (d4) { + if (d2) { + if (d0) { + /* 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 */ + z1 = MULTIPLY(d2 + d6, FIX_0_541196100); + tmp2 = z1 + MULTIPLY(-d6, FIX_1_847759065); + tmp3 = z1 + MULTIPLY(d2, FIX_0_765366865); + + tmp0 = d4 << CONST_BITS; + + tmp10 = tmp0 + tmp3; + tmp13 = tmp0 - tmp3; + tmp11 = tmp2 - tmp0; + tmp12 = -(tmp0 + tmp2); + } + } else { + if (d0) { + /* 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 { + /* d0 == 0, d2 == 0, d4 != 0, d6 != 0 */ + tmp2 = MULTIPLY(-d6, FIX_1_306562965); + tmp3 = MULTIPLY(d6, FIX_0_541196100); + + tmp0 = d4 << CONST_BITS; + + tmp10 = tmp0 + tmp3; + tmp13 = tmp0 - tmp3; + tmp11 = tmp2 - tmp0; + tmp12 = -(tmp0 + tmp2); + } + } + } else { + if (d2) { + if (d0) { + /* 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 << CONST_BITS; + + tmp10 = tmp0 + tmp3; + tmp13 = tmp0 - tmp3; + tmp11 = tmp0 + tmp2; + tmp12 = tmp0 - tmp2; + } else { + /* 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); + + tmp10 = tmp3; + tmp13 = -tmp3; + tmp11 = tmp2; + tmp12 = -tmp2; + } + } else { + if (d0) { + /* d0 != 0, d2 == 0, d4 == 0, d6 != 0 */ + tmp2 = MULTIPLY(-d6, FIX_1_306562965); + tmp3 = MULTIPLY(d6, FIX_0_541196100); + + tmp0 = d0 << CONST_BITS; + + tmp10 = tmp0 + tmp3; + tmp13 = tmp0 - tmp3; + tmp11 = tmp0 + tmp2; + tmp12 = tmp0 - tmp2; + } else { + /* d0 == 0, d2 == 0, d4 == 0, d6 != 0 */ + tmp2 = MULTIPLY(-d6, FIX_1_306562965); + tmp3 = MULTIPLY(d6, FIX_0_541196100); + + tmp10 = tmp3; + tmp13 = -tmp3; + tmp11 = tmp2; + tmp12 = -tmp2; + } + } + } + } else { + if (d4) { + if (d2) { + if (d0) { + /* 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 */ + tmp2 = MULTIPLY(d2, FIX_0_541196100); + tmp3 = MULTIPLY(d2, FIX_1_306562965); + + tmp0 = d4 << CONST_BITS; + + tmp10 = tmp0 + tmp3; + tmp13 = tmp0 - tmp3; + tmp11 = tmp2 - tmp0; + tmp12 = -(tmp0 + tmp2); + } + } else { + if (d0) { + /* d0 != 0, d2 == 0, d4 != 0, d6 == 0 */ + tmp10 = tmp13 = (d0 + d4) << CONST_BITS; + tmp11 = tmp12 = (d0 - d4) << CONST_BITS; + } else { + /* d0 == 0, d2 == 0, d4 != 0, d6 == 0 */ + tmp10 = tmp13 = d4 << CONST_BITS; + tmp11 = tmp12 = -tmp10; + } + } + } else { + if (d2) { + if (d0) { + /* d0 != 0, d2 != 0, d4 == 0, d6 == 0 */ + tmp2 = MULTIPLY(d2, FIX_0_541196100); + tmp3 = MULTIPLY(d2, FIX_1_306562965); + + tmp0 = d0 << CONST_BITS; + + tmp10 = tmp0 + tmp3; + tmp13 = tmp0 - tmp3; + tmp11 = tmp0 + tmp2; + tmp12 = tmp0 - tmp2; + } else { + /* d0 == 0, d2 != 0, d4 == 0, d6 == 0 */ + tmp2 = MULTIPLY(d2, FIX_0_541196100); + tmp3 = MULTIPLY(d2, FIX_1_306562965); + + tmp10 = tmp3; + tmp13 = -tmp3; + tmp11 = tmp2; + tmp12 = -tmp2; + } + } else { + if (d0) { + /* d0 != 0, d2 == 0, d4 == 0, d6 == 0 */ + tmp10 = tmp13 = tmp11 = tmp12 = d0 << CONST_BITS; + } else { + /* d0 == 0, d2 == 0, d4 == 0, d6 == 0 */ + tmp10 = tmp13 = tmp11 = tmp12 = 0; + } + } + } + } + + /* Final output stage: inputs are tmp10..tmp13, tmp0..tmp3 */ + + dataptr[DCTSTRIDE*0] = (DCTELEM) DESCALE(tmp10, + CONST_BITS+PASS1_BITS+3); + dataptr[DCTSTRIDE*1] = (DCTELEM) DESCALE(tmp11, + CONST_BITS+PASS1_BITS+3); + dataptr[DCTSTRIDE*2] = (DCTELEM) DESCALE(tmp12, + CONST_BITS+PASS1_BITS+3); + dataptr[DCTSTRIDE*3] = (DCTELEM) DESCALE(tmp13, + CONST_BITS+PASS1_BITS+3); + + dataptr++; /* advance pointer to next column */ + } +} + + #undef FIX #undef CONST_BITS |