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Hamming Distance using 16 bit accumulators

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Summing 16 bit hamming codes restricts the maximum length,
but saves an inner loop instruction.  The outer loop can sum the
values.

32 bit Neon
Now BenchmarkHammingDistance_Opt (78 ms)
Was BenchmarkHammingDistance_Opt (92 ms)

64 bit Neon
Now BenchmarkHammingDistance_Opt (85 ms)
Was BenchmarkHammingDistance_Opt (92 ms)

R=wangcheng@google.com
TBR=kjellander@chromium.org
BUG=libyuv:701
TEST=BenchmarkHammingDistance

Change-Id: Ie40f0eac2f3339c33b833b42af5d394b122066ae
Reviewed-on: https://chromium-review.googlesource.com/526932
Reviewed-by: Frank Barchard <fbarchard@google.com>
Reviewed-by: Cheng Wang <wangcheng@google.com>
Commit-Queue: Frank Barchard <fbarchard@google.com>
This commit is contained in:
Frank Barchard 2017-06-07 15:19:25 -07:00 committed by Commit Bot
parent 790e0634a8
commit d981495b42
4 changed files with 11 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
README.chromium
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@ -1,6 +1,6 @@
Name: libyuv Name: libyuv
URL: http://code.google.com/p/libyuv/ URL: http://code.google.com/p/libyuv/
Version: 1659 Version: 1660
License: BSD License: BSD
License File: LICENSE License File: LICENSE

2
include/libyuv/version.h
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@ -11,6 +11,6 @@
#ifndef INCLUDE_LIBYUV_VERSION_H_ #ifndef INCLUDE_LIBYUV_VERSION_H_
#define INCLUDE_LIBYUV_VERSION_H_ #define INCLUDE_LIBYUV_VERSION_H_
#define LIBYUV_VERSION 1659 #define LIBYUV_VERSION 1660
#endif // INCLUDE_LIBYUV_VERSION_H_ #endif // INCLUDE_LIBYUV_VERSION_H_

11
source/compare_neon.cc
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@ -22,12 +22,12 @@ extern "C" {
!defined(__aarch64__) !defined(__aarch64__)
// 256 bits at a time // 256 bits at a time
// uses short accumulator which restricts count to 131 KB
uint32 HammingDistance_NEON(const uint8* src_a, const uint8* src_b, int count) { uint32 HammingDistance_NEON(const uint8* src_a, const uint8* src_b, int count) {
uint32 diff; uint32 diff;
asm volatile ( asm volatile (
// Load constants. "vmov.u16 q4, #0 \n" // accumulator
"vmov.u8 q4, #0 \n" // accumulator
"1: \n" "1: \n"
"vld1.8 {q0, q1}, [%0]! \n" "vld1.8 {q0, q1}, [%0]! \n"
@ -38,13 +38,12 @@ uint32 HammingDistance_NEON(const uint8* src_a, const uint8* src_b, int count) {
"vcnt.i8 q1, q1 \n" "vcnt.i8 q1, q1 \n"
"subs %2, %2, #32 \n" "subs %2, %2, #32 \n"
"vadd.u8 q0, q0, q1 \n" // 16 byte counts "vadd.u8 q0, q0, q1 \n" // 16 byte counts
"vpaddl.u8 q0, q0 \n" // 8 shorts "vpadal.u8 q4, q0 \n" // 8 shorts
"vpadal.u16 q4, q0 \n" // 4 ints
"bgt 1b \n" "bgt 1b \n"
"vpadd.u32 d0, d8, d9 \n" "vpaddl.u16 q0, q4 \n" // 4 ints
"vpadd.u32 d0, d0, d1 \n"
"vpadd.u32 d0, d0, d0 \n" "vpadd.u32 d0, d0, d0 \n"
// Move distance to return register.
"vmov.32 %3, d0[0] \n" "vmov.32 %3, d0[0] \n"
: "+r"(src_a), : "+r"(src_a),

8
source/compare_neon64.cc
View File

@ -21,10 +21,11 @@ extern "C" {
#if !defined(LIBYUV_DISABLE_NEON) && defined(__aarch64__) #if !defined(LIBYUV_DISABLE_NEON) && defined(__aarch64__)
// 256 bits at a time // 256 bits at a time
// uses short accumulator which restricts count to 131 KB
uint32 HammingDistance_NEON(const uint8* src_a, const uint8* src_b, int count) { uint32 HammingDistance_NEON(const uint8* src_a, const uint8* src_b, int count) {
uint32 diff; uint32 diff;
asm volatile ( asm volatile (
"movi v4.4s, #0 \n" "movi v4.8h, #0 \n"
"1: \n" "1: \n"
"ld1 {v0.16b, v1.16b}, [%0], #32 \n" "ld1 {v0.16b, v1.16b}, [%0], #32 \n"
@ -35,11 +36,10 @@ uint32 HammingDistance_NEON(const uint8* src_a, const uint8* src_b, int count) {
"cnt v1.16b, v1.16b \n" "cnt v1.16b, v1.16b \n"
"subs %w2, %w2, #32 \n" "subs %w2, %w2, #32 \n"
"add v0.16b, v0.16b, v1.16b \n" "add v0.16b, v0.16b, v1.16b \n"
"uaddlp v0.8h, v0.16b \n" "uadalp v4.8h, v0.16b \n"
"uadalp v4.4s, v0.8h \n"
"b.gt 1b \n" "b.gt 1b \n"
"addv s4, v4.4s \n" "uaddlv s4, v4.8h \n"
"fmov %w3, s4 \n" "fmov %w3, s4 \n"
: "+r"(src_a), : "+r"(src_a),
"+r"(src_b), "+r"(src_b),