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| /* SPDX-License-Identifier: GPL-2.0 */
| /*
| * 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 <asm/export.h>
| #include <asm/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
| EXPORT_SYMBOL(strchr)
|
|
