Rewrote vfprintf() in assembler

git-svn-id: svn://svn.cc65.org/cc65/trunk@511 b7a2c559-68d2-44c3-8de9-860c34a00d81
2026-04-25 22:18:27 +00:00 · 2000-12-01 15:05:46 +00:00
parent 32fb9e74f0
commit 9333d5a839
5 changed files with 161 additions and 49 deletions
@@ -0,0 +1,158 @@
+;
+; int vprintf (FILE* f, const char* Format, va_list ap);
+;
+; Ullrich von Bassewitz, 1.12.2000
+;
+
+	.export	      	_vfprintf
+	.import	      	pushax, popax, push1
+	.import	      	_fwrite, __printf
+	.importzp     	sp, ptr1, ptr2
+
+	.macpack      	generic
+
+
+.data
+
+; ----------------------------------------------------------------------------
+;
+; Static data for the _vfprintf routine
+;
+
+outdesc:			; Static outdesc structure
+	.word	0		; ccount
+	.word	out		; Output function pointer
+	.word	0		; ptr
+	.word	0		; uns
+
+.code
+
+; ----------------------------------------------------------------------------
+; Callback routine used for the actual output.
+;
+; static void out (struct outdesc* d, const char* buf, unsigned count)
+; /* Routine used for writing */
+; {
+;     /* Write to the file */
+;     if (fwrite (buf, count, 1, (FILE*) d->ptr) == -1) {
+;         d->ccount = -1;
+;     } else {
+;         d->ccount += count;
+;     }
+; }
+
+out:
+
+; About to call
+;
+; 	fwrite (buf, count, 1, (FILE*) d->ptr);
+;
+; Since Buf and Count are already in place, we will just push the last
+; two parameters. The fwrite function will remove Buf and Count on exit.
+
+  	jsr	push1
+  	ldy    	#7     	       	; Offset of D+1 on stack
+  	lda	(sp),y
+  	sta	ptr1+1
+  	dey	   		; Offset of D on stack (6)
+  	lda	(sp),y
+  	sta	ptr1			       
+  	dey	   		; Offset of ptr+1 in struct outdesc (5)
+  	lda	(ptr1),y
+  	tax
+  	dey
+  	lda	(ptr1),y
+  	jsr	pushax		; Push D->ptr
+  	jsr	_fwrite
+       	sta	ptr2		; Save function result
+	stx	ptr2+1
+
+; Pop the last parameter from stack and store it in ptr1. This means that
+; the stack is clean now.
+
+	jsr	popax
+	sta	ptr1
+	stx	ptr1+1
+
+; Load the offset of ccount in struct outdesc
+
+	ldy	#$00
+
+; Check the return code. Checking the hig byte against $FF is ok here.
+
+       	lda	ptr2+1
+ 	cmp	#$FF
+	bne	@Ok
+
+; We had an error. Store -1 into d->ccount
+
+	sta	(ptr1),y
+	iny
+	sta	(ptr1),y
+	rts
+
+; Result was ok, count bytes written
+
+@Ok:	lda	(ptr1),y
+	add	ptr1
+	sta	(ptr1),y
+	iny
+	lda	(ptr1),y
+	adc	ptr1+1
+	sta	(ptr1),y
+	rts
+
+
+; ----------------------------------------------------------------------------
+; Callback routine used for the actual output.
+;
+; int vfprintf (FILE* f, const char* format, va_list ap)
+; {
+;     struct outdesc d;
+;
+;     /* Setup descriptor */
+;     d.fout = out;
+;     d.ptr  = f;
+;
+;     /* Do formatting and output */
+;     _printf (&d, format, ap);
+;
+;     /* Return bytes written */
+;     return d.ccount;
+; }
+
+_vfprintf:
+	pha			; Save low byte of ap
+
+; Setup the outdesc structure
+
+	lda	#0
+	sta	outdesc
+	sta	outdesc+1	; Clear ccount
+
+; Reorder the stack. Replace f on the stack by &d, so the stack frame is
+; exactly as _printf expects it. Parameters will get dropped by _printf.
+
+	ldy	#2		;
+	lda	(sp),y		; Low byte of f
+	sta	outdesc+4	;
+	lda	#<outdesc
+	sta	(sp),y
+	iny
+	lda	(sp),y	 	; High byte of f
+	sta	outdesc+5
+	lda	#>outdesc
+	sta	(sp),y
+
+; Restore low byte of ap and call _printf
+
+	pla
+	jsr	__printf
+
+; Return the number of bytes written
+
+	lda	outdesc
+	ldx	outdesc+1
+	rts
+
+