mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-12-05 10:04:12 +08:00
1da177e4c3
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
88 lines
2.7 KiB
ArmAsm
88 lines
2.7 KiB
ArmAsm
/*
|
|
* arch/alpha/lib/strrchr.S
|
|
* Contributed by Richard Henderson (rth@tamu.edu)
|
|
*
|
|
* Return the address of the last occurrence of a given character
|
|
* within a null-terminated string, or null if it is not found.
|
|
*/
|
|
|
|
#include <asm/regdef.h>
|
|
|
|
.set noreorder
|
|
.set noat
|
|
|
|
.align 3
|
|
.ent strrchr
|
|
.globl strrchr
|
|
strrchr:
|
|
.frame sp, 0, ra
|
|
.prologue 0
|
|
|
|
zapnot a1, 1, a1 # e0 : zero extend our test character
|
|
mov zero, t6 # .. e1 : t6 is last match aligned addr
|
|
sll a1, 8, t5 # e0 : replicate our test character
|
|
mov zero, t8 # .. e1 : t8 is last match byte compare mask
|
|
or t5, a1, a1 # e0 :
|
|
ldq_u t0, 0(a0) # .. e1 : load first quadword
|
|
sll a1, 16, t5 # e0 :
|
|
andnot a0, 7, v0 # .. e1 : align source addr
|
|
or t5, a1, a1 # e0 :
|
|
lda t4, -1 # .. e1 : build garbage mask
|
|
sll a1, 32, t5 # e0 :
|
|
cmpbge zero, t0, t1 # .. e1 : bits set iff byte == zero
|
|
mskqh t4, a0, t4 # e0 :
|
|
or t5, a1, a1 # .. e1 : character replication complete
|
|
xor t0, a1, t2 # e0 : make bytes == c zero
|
|
cmpbge zero, t4, t4 # .. e1 : bits set iff byte is garbage
|
|
cmpbge zero, t2, t3 # e0 : bits set iff byte == c
|
|
andnot t1, t4, t1 # .. e1 : clear garbage from null test
|
|
andnot t3, t4, t3 # e0 : clear garbage from char test
|
|
bne t1, $eos # .. e1 : did we already hit the terminator?
|
|
|
|
/* Character search main loop */
|
|
$loop:
|
|
ldq t0, 8(v0) # e0 : load next quadword
|
|
cmovne t3, v0, t6 # .. e1 : save previous comparisons match
|
|
cmovne t3, t3, t8 # e0 :
|
|
addq v0, 8, v0 # .. e1 :
|
|
xor t0, a1, t2 # e0 :
|
|
cmpbge zero, t0, t1 # .. e1 : bits set iff byte == zero
|
|
cmpbge zero, t2, t3 # e0 : bits set iff byte == c
|
|
beq t1, $loop # .. e1 : if we havnt seen a null, loop
|
|
|
|
/* Mask out character matches after terminator */
|
|
$eos:
|
|
negq t1, t4 # e0 : isolate first null byte match
|
|
and t1, t4, t4 # e1 :
|
|
subq t4, 1, t5 # e0 : build a mask of the bytes upto...
|
|
or t4, t5, t4 # e1 : ... and including the null
|
|
|
|
and t3, t4, t3 # e0 : mask out char matches after null
|
|
cmovne t3, t3, t8 # .. e1 : save it, if match found
|
|
cmovne t3, v0, t6 # e0 :
|
|
|
|
/* Locate the address of the last matched character */
|
|
|
|
/* Retain the early exit for the ev4 -- the ev5 mispredict penalty
|
|
is 5 cycles -- the same as just falling through. */
|
|
beq t8, $retnull # .. e1 :
|
|
|
|
and t8, 0xf0, t2 # e0 : binary search for the high bit set
|
|
cmovne t2, t2, t8 # .. e1 (zdb)
|
|
cmovne t2, 4, t2 # e0 :
|
|
and t8, 0xcc, t1 # .. e1 :
|
|
cmovne t1, t1, t8 # e0 :
|
|
cmovne t1, 2, t1 # .. e1 :
|
|
and t8, 0xaa, t0 # e0 :
|
|
cmovne t0, 1, t0 # .. e1 (zdb)
|
|
addq t2, t1, t1 # e0 :
|
|
addq t6, t0, v0 # .. e1 : add our aligned base ptr to the mix
|
|
addq v0, t1, v0 # e0 :
|
|
ret # .. e1 :
|
|
|
|
$retnull:
|
|
mov zero, v0 # e0 :
|
|
ret # .. e1 :
|
|
|
|
.end strrchr
|