Module Name: src
Committed By: dennis
Date: Tue Oct 28 20:25:36 UTC 2014
Modified Files:
src/sys/arch/riscv/include: byte_swap.h
Log Message:
Shave an instruction from the generated code for the 32 bit byte
swap inline. Prune 5 or 9 instructions (depending on what you count)
from the 64 bit byte swap inline.
To generate a diff of this commit:
cvs rdiff -u -r1.2 -r1.3 src/sys/arch/riscv/include/byte_swap.h
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/arch/riscv/include/byte_swap.h
diff -u src/sys/arch/riscv/include/byte_swap.h:1.2 src/sys/arch/riscv/include/byte_swap.h:1.3
--- src/sys/arch/riscv/include/byte_swap.h:1.2 Tue Oct 28 19:46:18 2014
+++ src/sys/arch/riscv/include/byte_swap.h Tue Oct 28 20:25:36 2014
@@ -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;
}
