Aren/NetBSD
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Shave an instruction from the generated code for the 32 bit byte

Browse Source 
swap inline.  Prune 5 or 9 instructions (depending on what you count)
from the 64 bit byte swap inline.
This commit is contained in:
dennis 2014-10-28 20:25:36 +00:00
parent 08bd07a048
commit ca2461272f
1 changed files with 11 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
sys/arch/riscv/include/byte_swap.h
View File

@ -1,4 +1,4 @@
/* $NetBSD: byte_swap.h,v 1.2 2014/10/28 19:46:18 dennis Exp $ */
/* $NetBSD: byte_swap.h,v 1.3 2014/10/28 20:25:36 dennis Exp $ */
/*-
* Copyright (c) 2014 The NetBSD Foundation, Inc.
@ -62,10 +62,12 @@ __BEGIN_DECLS
static __inline uint64_t
__byte_swap_u64_variable(uint64_t v)
{
v = ((v & 0x000000ff) << (56 - 0)) | ((v >> (56 - 0)) & 0x000000ff)
| ((v & 0x0000ff00) << (48 - 8)) | ((v >> (48 - 8)) & 0x0000ff00)
| ((v & 0x00ff0000) << (40 - 16)) | ((v >> (40 - 16)) & 0x00ff0000)
| ((v & 0xff000000) << (32 - 24)) | ((v >> (32 - 24)) & 0xff000000);
const uint64_t m1 = 0x0000ffff0000ffffull;
const uint64_t m0 = 0x00ff00ff00ff00ffull;
v = (v >> 32) | (v << 32);
v = ((v >> 16) & m1) | ((v & m1) << 16);
v = ((v >> 8) & m0) | ((v & m0) << 8);
return v;
}
@ -74,8 +76,10 @@ __byte_swap_u64_variable(uint64_t v)
static __inline uint32_t
__byte_swap_u32_variable(uint32_t v)
{
v = ((v & 0x00ff) << (24 - 0)) | ((v >> (24 - 0)) & 0x00ff)
| ((v & 0xff00) << (16 - 8)) | ((v >> (16 - 8)) & 0xff00);
const uint32_t m = 0xff00ff;
v = (v >> 16) | (v << 16);
v = ((v >> 8) & m) | ((v & m) << 8);
return v;
}