Add fmemset in asm for OWC

elks/tools/objtools/ecc

@@ -51,8 +51,8 @@ CFLAGS="\
 
 ASFLAGS="\
     -0                          \
-    -O                          \
     -j                          \
+    -O                          \
     -w-                         \
     "
 

libc/include/string.h

@@ -29,6 +29,7 @@ int memcmp(const void*, const void*, size_t);
 void * memmove(void*, const void*, size_t);
 
 void __far *fmemset(void __far *buf, int c, size_t l);
+int fmemcmp(void __far *s1, void __far *s2, size_t n);  /* Watcom C only, in ASM */
 
 /* Error messages */
 char * strerror(int);

libc/watcom/asm/fmemcmp.asm

@@ -0,0 +1,46 @@
+; int fmemcmp(void __far *s1, void __far *s2, size_t n)
+;   returns 0 on match, otherwise nonzero
+;
+; 2 Jan 2025 Greg Haerr
+
+include mdef.inc
+include struct.inc
+
+        modstart    fmemcmp
+
+        xdefp   "C",fmemcmp
+        defpe    fmemcmp
+
+; s1 in DX:AX, s2 in CX:BX, n on stack
+        push    bp
+        mov     bp,sp
+        push    si
+        push    di
+
+        mov     ds,dx
+        mov     si,ax
+        mov     es,cx
+        mov     di,bx
+if _MODEL and _BIG_CODE
+        mov     cx,6[bp]    ; n
+else
+        mov     cx,4[bp]    ; n
+endif
+        cld
+        repz cmpsb
+        jz     L1           ; equal
+
+        mov     ax,1        ; not equal, returns nonzero
+        pop     di
+        pop     si
+        pop     bp
+        ret     2
+L1:     xor     ax,ax
+        pop     di
+        pop     si
+        pop     bp
+        ret     2
+
+fmemcmp endp
+        endmod
+        end