Add a new subroutine called get_index.

This subroutine gets the index of a given character
from a string.

This will help in replacing some routines like
get_ctrlidx, isdelm, and isdelm2.

1 files changed, 35 insertions, 0 deletions

diff --git a/programs/sub-suite/utils.s b/programs/sub-suite/utils.s
index 8f4a643..3621051 100644
--- a/programs/sub-suite/utils.s
+++ b/programs/sub-suite/utils.s
@@ -316,6 +316,41 @@ findramend:
 	mov a, d	; Return the end of RAM pointer.
 	rts		; End of findramend.
 
+; get_index: Get the index of a given character from a string.
+; Input: D = Pointer to string. S = Character to look for. F = Indexing mode.
+; Output: A = Index of the character in the string, if found.
+; Caller preserved registers: D, S, F.
+; Callee preserved registers: B.
+;
+; Indexing modes:
+; 0 = Increment mode.
+; 1 = Boolean mode.
+; 2 = Increment mode, plus one.
+
+get_index:
+	phb.q		; Preserve B.
+	and #0		; Reset A.
+	tab		; Reset B.
+	cmp f, #2	; Is the index starting at one?
+	leq #1		; Set the index to one if so.
+	dec		; Decrement the index to account for incrementing at the start.
+@loop:
+	inc		; Increment the index.
+	mov b, (d+a)	; Are we at the end of the string?
+	beq @is_bool	; Yes, so check if we're using boolean mode.
+@@loop:
+	cmp s, b	; Is this character the same as the one we're looking for?
+	bne @loop	; No, so keep looping.
+@is_bool:
+	and f, f	; Are we using boolean mode?
+	beq @end	; No, so we're done.
+@bool:
+	cmp s, b	; Is this character the same as the one we're looking for?
+	set a, eq	; Set the index to true if so.
+@end:
+	plb.q		; Restore B.
+	rts		; End of get_index.
+
 
 print_sfast:
 	pha.q			; Preserve A.