From b5d259bafb1b3bcf4eb2c1ddc92d14b3c891fd49 Mon Sep 17 00:00:00 2001
From: Colin Leroy-Mira <colin@colino.net>
Date: Mon, 18 Mar 2024 19:52:04 +0100
Subject: [PATCH] Implement strcasestr as part of strstr

---
 libsrc/common/strcasestr.c | 36 --------------------------
 libsrc/common/strstr.s     | 53 +++++++++++++++++++++++++-------------
 libsrc/common/tolower.s    |  6 ++---
 3 files changed, 38 insertions(+), 57 deletions(-)
 delete mode 100644 libsrc/common/strcasestr.c

diff --git a/libsrc/common/strcasestr.c b/libsrc/common/strcasestr.c
deleted file mode 100644
index 693b43a37..000000000
--- a/libsrc/common/strcasestr.c
+++ /dev/null
@@ -1,36 +0,0 @@
-/*
-** strcasestr.c
-**
-** Colin Leroy-Mira, 2024
-*/
-
-
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-
-
-
-/*****************************************************************************/
-/*                                   Code                                    */
-/*****************************************************************************/
-
-
-
-char* __fastcall__ strcasestr(const char *str, const char *substr) {
-  size_t len_a = strlen(str);
-  size_t len_b = strlen(substr);
-  const char *end_str;
-
-  if (len_a < len_b)
-    return NULL;
-
-  len_a -= len_b;
-
-  for (end_str = str + len_a + 1; str < end_str; str++) {
-    if (!strncasecmp(str, substr, len_b))
-      return (char *)str;
-  }
-  return NULL;
-}
diff --git a/libsrc/common/strstr.s b/libsrc/common/strstr.s
index 84f633245..9cc9c0d33 100644
--- a/libsrc/common/strstr.s
+++ b/libsrc/common/strstr.s
@@ -4,11 +4,18 @@
 ; char* strstr (const char* haystack, const char* needle);
 ;
 
-        .export         _strstr
-        .import         popptr1
-        .importzp       ptr1, ptr2, ptr3, ptr4, tmp1
+        .export         _strstr, _strcasestr
+        .import         popptr1, _tolower
+        .importzp       ptr1, ptr2, ptr3, ptr4, tmp1, tmp2, tmp3
 
 _strstr:
+        ldy     #$01
+        bne     :+
+_strcasestr:
+        ldy     #$00
+:
+        sty     tmp2            ; Set case sensitivity
+
         sta     ptr2            ; Save needle
         stx     ptr2+1
         sta     ptr4            ; Setup temp copy for later
@@ -24,10 +31,19 @@ _strstr:
 ; Search for the beginning of the string (this is not an optimal search
 ; strategy [in fact, it's pretty dumb], but it's simple to implement).
 
-        sta     tmp1            ; Save start of needle
+        ldx     tmp2            ; Lowercase if needed
+        bne     :+
+        jsr     _tolower
+
+:       sta     tmp1            ; Save start of needle
 @L1:    lda     (ptr1),y        ; Get next char from haystack
         beq     @NotFound       ; Jump if end
-        cmp     tmp1            ; Start of needle found?
+
+        ldx     tmp2            ; Lowercase if needed
+        bne     :+
+        jsr     _tolower
+
+:       cmp     tmp1            ; Start of needle found?
         beq     @L2             ; Jump if so
         iny                     ; Next char
         bne     @L1
@@ -43,7 +59,7 @@ _strstr:
         bcc     @L3
         inc     ptr1+1
 
-; ptr1 points to the start of needle now. Setup temporary pointers for the
+; ptr1 points to the start of needle in haystack now. Setup temporary pointers for the
 ; search. The low byte of ptr4 is already set.
 
 @L3:    sta     ptr3
@@ -57,7 +73,19 @@ _strstr:
 
 @L4:    lda     (ptr4),y        ; Get char from needle
         beq     @Found          ; Jump if end of needle (-> found)
-        cmp     (ptr3),y        ; Compare with haystack
+
+        ldx     tmp2            ; Lowercase if needed
+        bne     :+
+        jsr     _tolower
+:       sta     tmp3
+
+        lda     (ptr3),y        ; Compare with haystack
+
+        ldx     tmp2            ; Lowercase if needed
+        bne     :+
+        jsr     _tolower
+
+:       cmp     tmp3
         bne     @L5             ; Jump if not equal
         iny                     ; Next char
         bne     @L4
@@ -82,14 +110,3 @@ _strstr:
         lda     #$00            ; return NULL
         tax
         rts
-
-
-
-
-
-
-
-
-
-
-
diff --git a/libsrc/common/tolower.s b/libsrc/common/tolower.s
index 828be1cb1..22b030da3 100644
--- a/libsrc/common/tolower.s
+++ b/libsrc/common/tolower.s
@@ -17,12 +17,12 @@
 _tolower:
         cpx     #$00            ; out of range?
         bne     @L2             ; if so, return the argument unchanged
-        tay                     ; save char
+        pha                     ; save char
         jsr     ctypemaskdirect ; get character classification
         and     #CT_UPPER       ; upper case char?
         beq     @L1             ; jump if no
-        tya                     ; restore char
+        pla                     ; restore char
         adc     #<('a'-'A')     ; make lower case char (ctypemaskdirect ensures carry clear)
         rts
-@L1:    tya                     ; restore char
+@L1:    pla                     ; restore char
 @L2:    rts