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/*
* arch/alpha/lib/strchr.S
* Contributed by Richard Henderson (rth@tamu.edu)
*
* Return the address of a given character within a null-terminated
* string, or null if it is not found.
*/
#include <alpha/regdef.h>
.set noreorder
.set noat
.align 3
.globl strchr
.ent strchr
strchr:
.frame sp, 0, ra
.prologue 0
zapnot a1, 1, a1 # e0 : zero extend the search character
ldq_u t0, 0(a0) # .. e1 : load first quadword
sll a1, 8, t5 # e0 : replicate the search character
andnot a0, 7, v0 # .. e1 : align our loop pointer
or t5, a1, a1 # e0 :
lda t4, -1 # .. e1 : build garbage mask
sll a1, 16, t5 # e0 :
cmpbge zero, t0, t2 # .. e1 : bits set iff byte == zero
mskqh t4, a0, t4 # e0 :
or t5, a1, a1 # .. e1 :
sll a1, 32, t5 # e0 :
cmpbge zero, t4, t4 # .. e1 : bits set iff byte is garbage
or t5, a1, a1 # e0 :
xor t0, a1, t1 # .. e1 : make bytes == c zero
cmpbge zero, t1, t3 # e0 : bits set iff byte == c
or t2, t3, t0 # e1 : bits set iff char match or zero match
andnot t0, t4, t0 # e0 : clear garbage bits
bne t0, $found # .. e1 (zdb)
$loop: ldq t0, 8(v0) # e0 :
addq v0, 8, v0 # .. e1 :
nop # e0 :
xor t0, a1, t1 # .. e1 (ev5 data stall)
cmpbge zero, t0, t2 # e0 : bits set iff byte == 0
cmpbge zero, t1, t3 # .. e1 : bits set iff byte == c
or t2, t3, t0 # e0 :
beq t0, $loop # .. e1 (zdb)
$found: negq t0, t1 # e0 : clear all but least set bit
and t0, t1, t0 # e1 (stall)
and t0, t3, t1 # e0 : bit set iff byte was the char
beq t1, $retnull # .. e1 (zdb)
and t0, 0xf0, t2 # e0 : binary search for that set bit
and t0, 0xcc, t3 # .. e1 :
and t0, 0xaa, t4 # e0 :
cmovne t2, 4, t2 # .. e1 :
cmovne t3, 2, t3 # e0 :
cmovne t4, 1, t4 # .. e1 :
addq t2, t3, t2 # e0 :
addq v0, t4, v0 # .. e1 :
addq v0, t2, v0 # e0 :
ret # .. e1 :
$retnull:
mov zero, v0 # e0 :
ret # .. e1 :
.end strchr
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