ref: ff03b72ed5f365a2ca052218e055fac678cf0e23
dir: /sys/src/libc/386/memchr.s/
TEXT memchr(SB),$0 MOVL n+8(FP), CX CMPL CX, $0 JEQ none MOVL p+0(FP), DI MOVBLZX c+4(FP), AX CLD /* * SCASB is memchr instruction */ REPN; SCASB JEQ found none: MOVL $0, AX RET found: MOVL DI, AX SUBL $1, AX RET