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-rw-r--r--libavcodec/jrevdct.c213
1 files changed, 213 insertions, 0 deletions
diff --git a/libavcodec/jrevdct.c b/libavcodec/jrevdct.c
index e6846a1d78..91780b2e44 100644
--- a/libavcodec/jrevdct.c
+++ b/libavcodec/jrevdct.c
@@ -940,3 +940,216 @@ void ff_j_rev_dct(DCTBLOCK data)
dataptr++; /* advance pointer to next column */
}
}
+
+#undef DCTSIZE
+#define DCTSIZE 4
+#define DCTSTRIDE 8
+
+void ff_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 int16_t *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. */
+ int16_t dcval = (int16_t) (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] = (int16_t) DESCALE(tmp10, CONST_BITS-PASS1_BITS);
+ dataptr[1] = (int16_t) DESCALE(tmp11, CONST_BITS-PASS1_BITS);
+ dataptr[2] = (int16_t) DESCALE(tmp12, CONST_BITS-PASS1_BITS);
+ dataptr[3] = (int16_t) 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 ff_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 ff_j_rev_dct1(DCTBLOCK data){
+ data[0] = (data[0] + 4)>>3;
+}
+
+#undef FIX
+#undef CONST_BITS
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