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TEXT strchr(SB), $-4
MOVBU c+4(FP), R1
CMP $0, R1
BEQ _null
_strchr: /* not looking for a null, byte at a time */
MOVBU.P 1(R0), R2
CMP R1, R2
BEQ _sub1
CMP $0, R2
BNE _strchr
_return0: /* character not found in string, return 0 */
MOVW $0, R0
RET
_null: /* looking for null, align */
AND.S $3, R0, R2
BEQ _aligned
MOVBU.P 1(R0), R4
CMP $0, R4
BEQ _sub1
B _null
_aligned:
MOVW $0xFF, R3 /* mask */
_loop:
MOVW.P 4(R0), R4 /* 4 at a time */
TST R4, R3 /* AND.S R2, R3, Rx */
TST.NE R4>>8, R3
TST.NE R4>>16, R3
TST.NE R4>>24, R3
BNE _loop
TST R4, R3 /* its somewhere, find it and correct */
BEQ _sub4
TST R4>>8, R3
BEQ _sub3
TST R4>>16, R3
BEQ _sub2
_sub1: /* compensate for pointer increment */
SUB $1, R0
RET
_sub2:
SUB $2, R0
RET
_sub3:
SUB $3, R0
RET
_sub4:
SUB $4, R0
RET
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