ref: 37166d5c1e4d3959cf26b8981bc6a545e511c92e
parent: e9c69ab10222c98ec11d94f25c3579f296244fb3
parent: cc80247f16ce83271e5c2043307dc65c8bb4bbf7
author: Yunqing Wang <yunqingwang@google.com>
date: Wed Jan 2 06:45:27 EST 2013
Merge "Switch the order of calculating 2-D inverse transform" into experimental
--- a/vp9/common/vp9_idctllm.c
+++ b/vp9/common/vp9_idctllm.c
@@ -399,10 +399,10 @@
}
/* Converted the transforms to integer form. */
-#define VERTICAL_SHIFT 14 // 16
-#define VERTICAL_ROUNDING ((1 << (VERTICAL_SHIFT - 1)) - 1)
-#define HORIZONTAL_SHIFT 17 // 15
+#define HORIZONTAL_SHIFT 14 // 16
#define HORIZONTAL_ROUNDING ((1 << (HORIZONTAL_SHIFT - 1)) - 1)
+#define VERTICAL_SHIFT 17 // 15
+#define VERTICAL_ROUNDING ((1 << (VERTICAL_SHIFT - 1)) - 1)
void vp9_ihtllm_c(const int16_t *input, int16_t *output, int pitch,
TX_TYPE tx_type, int tx_dim) {int i, j, k;
@@ -444,41 +444,47 @@
break;
}
- /* vertical transformation */
+ /* 2-D inverse transform X = M1*Z*Transposed_M2 is calculated in 2 steps
+ * from right to left:
+ * 1. horizontal transform: Y= Z*Transposed_M2
+ * 2. vertical transform: X = M1*Y
+ * In SIMD, doing this way could eliminate the transpose needed if it is
+ * calculated from left to right.
+ */
+ /* Horizontal transformation */
for (j = 0; j < tx_dim; j++) { for (i = 0; i < tx_dim; i++) {int temp = 0;
for (k = 0; k < tx_dim; k++) {- temp += ptv[k] * ip[(k * tx_dim)];
+ temp += ip[k] * pth[k];
}
- im[i] = (int16_t)((temp + VERTICAL_ROUNDING) >> VERTICAL_SHIFT);
- ip++;
+ /* Calculate im and store it in its transposed position. */
+ im[i] = (int16_t)((temp + HORIZONTAL_ROUNDING) >> HORIZONTAL_SHIFT);
+ ip += tx_dim;
}
- im += tx_dim; // 16
- ptv += tx_dim;
+ im += tx_dim;
+ pth += tx_dim;
ip = input;
}
- /* horizontal transformation */
+ /* Vertical transformation */
im = &imbuf[0];
- for (j = 0; j < tx_dim; j++) {- const int16_t *pthc = pth;
-
- for (i = 0; i < tx_dim; i++) {+ for (i = 0; i < tx_dim; i++) {+ for (j = 0; j < tx_dim; j++) {int temp = 0;
for (k = 0; k < tx_dim; k++) {- temp += im[k] * pthc[k];
+ temp += ptv[k] * im[k];
}
- op[i] = (int16_t)((temp + HORIZONTAL_ROUNDING) >> HORIZONTAL_SHIFT);
- pthc += tx_dim;
+ op[j] = (int16_t)((temp + VERTICAL_ROUNDING) >> VERTICAL_SHIFT);
+ im += tx_dim;
}
-
- im += tx_dim; // 16
+ im = &imbuf[0];
+ ptv += tx_dim;
op += shortpitch;
}
}
--
⑨