Initial revision

lib/i86/string/strchr.s

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+!	strchr()					Author: Kees J. Bot
+!								27 Jan 1994
+.sect .text; .sect .rom; .sect .data; .sect .bss
+
+! char *strchr(const char *s, int c)
+!	Look for a character in a string.
+!
+.sect .text
+.define _strchr
+_strchr:
+	push	bp
+	mov	bp, sp
+	push	di
+	cld
+	mov	di, 4(bp)	! di = string
+	mov	dx, #16		! Look at small chunks of the string
+next:	shl	dx, #1		! Chunks become bigger each time
+	mov	cx, dx
+	xorb	al, al		! Look for the zero at the end
+  repne	scasb
+	pushf			! Remember the flags
+	sub	cx, dx
+	neg	cx		! Some or all of the chunk
+	sub	di, cx		! Step back
+	movb	al, 6(bp)	! The character to look for
+  repne	scasb
+	je	found
+	popf			! Did we find the end of string earlier?
+	jne	next		! No, try again
+	xor	ax, ax		! Return NULL
+	pop	di
+	pop	bp
+	ret
+found:	pop	ax		! Get rid of those flags
+	lea	ax, -1(di)	! Address of byte found
+	pop	di
+	pop	bp
+	ret