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Scale down by 2 linear use 'half add' to average pixels.

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Use ld2 to load even and odd pixels into different registers
and hadd to half add them to each other.

Previously used paired and shift.

TBR=kjellander@chromium.org
BUG=libyuv:723
TEST=ScaleDownBy2_Linear

Change-Id: I3ec72bcf7d4c746837217496c301eb4e4ad963cf
Reviewed-on: https://chromium-review.googlesource.com/644113
Reviewed-by: Cheng Wang <wangcheng@google.com>
This commit is contained in:
Frank Barchard 2017-08-30 11:50:47 -07:00
parent e200738d82
commit 1c85f98846
1 changed files with 9 additions and 22 deletions
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31
source/scale_neon.cc
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@ -51,14 +51,9 @@ void ScaleRowDown2Linear_NEON(const uint8* src_ptr,
(void)src_stride;
asm volatile(
"1: \n"
"vld1.8 {q0, q1}, [%0]! \n" // load pixels and post
// inc
"vld2.8 {q0, q1}, [%0]! \n" // load 32 pixels
"subs %2, %2, #16 \n" // 16 processed per loop
"vpaddl.u8 q0, q0 \n" // add adjacent
"vpaddl.u8 q1, q1 \n"
"vrshrn.u16 d0, q0, #1 \n" // downshift, round and
// pack
"vrshrn.u16 d1, q1, #1 \n"
"vrhadd.u8 q0, q0, q1 \n" // rounding half add
"vst1.8 {q0}, [%1]! \n"
"bgt 1b \n"
: "+r"(src_ptr), // %0
@ -714,8 +709,8 @@ void ScaleARGBRowDown2_NEON(const uint8* src_ptr,
"vld2.32 {q0, q1}, [%0]! \n"
"vld2.32 {q2, q3}, [%0]! \n"
"subs %2, %2, #8 \n" // 8 processed per loop
"vst1.8 {q1}, [%1]! \n" // store odd pixels
"vst1.8 {q3}, [%1]! \n"
"vst1.32 {q1}, [%1]! \n" // store odd pixels
"vst1.32 {q3}, [%1]! \n"
"bgt 1b \n"
: "+r"(src_ptr), // %0
"+r"(dst), // %1
@ -732,20 +727,12 @@ void ScaleARGBRowDown2Linear_NEON(const uint8* src_argb,
(void)src_stride;
asm volatile(
"1: \n"
"vld4.8 {d0, d2, d4, d6}, [%0]! \n" // load 8 ARGB pixels.
"vld4.8 {d1, d3, d5, d7}, [%0]! \n" // load next 8 ARGB
// pixels.
"vld4.32 {d0, d2, d4, d6}, [%0]! \n" // load 8 ARGB pixels.
"vld4.32 {d1, d3, d5, d7}, [%0]! \n" // load next 8 ARGB
"subs %2, %2, #8 \n" // 8 processed per loop
"vpaddl.u8 q0, q0 \n" // B 16 bytes -> 8 shorts.
"vpaddl.u8 q1, q1 \n" // G 16 bytes -> 8 shorts.
"vpaddl.u8 q2, q2 \n" // R 16 bytes -> 8 shorts.
"vpaddl.u8 q3, q3 \n" // A 16 bytes -> 8 shorts.
"vrshrn.u16 d0, q0, #1 \n" // downshift, round and
// pack
"vrshrn.u16 d1, q1, #1 \n"
"vrshrn.u16 d2, q2, #1 \n"
"vrshrn.u16 d3, q3, #1 \n"
"vst4.8 {d0, d1, d2, d3}, [%1]! \n"
"vrhadd.u8 q0, q0, q1 \n" // rounding half add
"vrhadd.u8 q1, q2, q3 \n" // rounding half add
"vst2.32 {q0, q1}, [%1]! \n"
"bgt 1b \n"
: "+r"(src_argb), // %0
"+r"(dst_argb), // %1