ref: 08507eb82a61e7e77000c44fcfef302a4967ec2c
parent: d5657905b695e0b1ffe8fa7682a0ba9cd231e981
parent: 45db71d0acd4705d554cec5828ceec3515791382
author: Yaowu Xu <[email protected]>
date: Mon Aug 31 12:38:36 EDT 2015
Merge "Expand the idct4_c() function in idct8_c()"
--- a/vpx_dsp/inv_txfm.c
+++ b/vpx_dsp/inv_txfm.c
@@ -170,16 +170,25 @@
step1[5] = WRAPLOW(dct_const_round_shift(temp1), 8);
step1[6] = WRAPLOW(dct_const_round_shift(temp2), 8);
- // stage 2 & stage 3 - even half
- idct4_c(step1, step1);
-
- // stage 2 - odd half
+ // stage 2
+ temp1 = (step1[0] + step1[2]) * cospi_16_64;
+ temp2 = (step1[0] - step1[2]) * cospi_16_64;
+ step2[0] = WRAPLOW(dct_const_round_shift(temp1), 8);
+ step2[1] = WRAPLOW(dct_const_round_shift(temp2), 8);
+ temp1 = step1[1] * cospi_24_64 - step1[3] * cospi_8_64;
+ temp2 = step1[1] * cospi_8_64 + step1[3] * cospi_24_64;
+ step2[2] = WRAPLOW(dct_const_round_shift(temp1), 8);
+ step2[3] = WRAPLOW(dct_const_round_shift(temp2), 8);
step2[4] = WRAPLOW(step1[4] + step1[5], 8);
step2[5] = WRAPLOW(step1[4] - step1[5], 8);
step2[6] = WRAPLOW(-step1[6] + step1[7], 8);
step2[7] = WRAPLOW(step1[6] + step1[7], 8);
- // stage 3 -odd half
+ // stage 3
+ step1[0] = WRAPLOW(step2[0] + step2[3], 8);
+ step1[1] = WRAPLOW(step2[1] + step2[2], 8);
+ step1[2] = WRAPLOW(step2[1] - step2[2], 8);
+ step1[3] = WRAPLOW(step2[0] - step2[3], 8);
step1[4] = step2[4];
temp1 = (step2[6] - step2[5]) * cospi_16_64;
temp2 = (step2[5] + step2[6]) * cospi_16_64;