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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 <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