From 5967b4845e0edd37b4eb6b73c873a4ef47f75fc7 Mon Sep 17 00:00:00 2001
From: uz <uz@b7a2c559-68d2-44c3-8de9-860c34a00d81>
Date: Sun, 27 Sep 2009 12:18:06 +0000
Subject: [PATCH] Let vsprintf call vsnprintf to save code.

git-svn-id: svn://svn.cc65.org/cc65/trunk@4247 b7a2c559-68d2-44c3-8de9-860c34a00d81
---
 libsrc/common/vsprintf.s | 159 +++++----------------------------------
 1 file changed, 19 insertions(+), 140 deletions(-)

diff --git a/libsrc/common/vsprintf.s b/libsrc/common/vsprintf.s
index 2e2752b43..c6084bdda 100644
--- a/libsrc/common/vsprintf.s
+++ b/libsrc/common/vsprintf.s
@@ -1,161 +1,40 @@
 ;
 ; int vsprintf (char* Buf, const char* Format, va_list ap);
 ;
-; Ullrich von Bassewitz, 1.12.2000
+; Ullrich von Bassewitz, 2009-09-26
 ;
 
    	.export	      	_vsprintf
-	.import	      	pushax, popax
-	.import	      	_memcpy, __printf
-	.importzp     	sp, ptr1
-
-	.macpack      	generic
-
-
-.data
-
-; ----------------------------------------------------------------------------
-;
-; Static data for the _vsprintf routine
-;
-
-outdesc:		 	; Static outdesc structure
-	.word	0	 	; ccount
-	.word	out	 	; Output function pointer
-	.word	0	 	; ptr
-	.word	$7FFF	 	; Buffer size (max int)
-
-.code
-
-; ----------------------------------------------------------------------------
-; Callback routine used for the actual output.
-;
-; static void out (struct outdesc* d, const char* buf, unsigned count)
-; /* Routine used for writing */
-; {
-;     /* String - be sure to check the size */
-;     while (count-- && d->ccount < d->uns) {
-;  	  ((char*) d->ptr) [d->ccount] = *buf;
-;  	  ++buf;
-;  	  ++d->ccount;
-;     }
-; }
-;
-; The assembler version assumes that the buffer is big enough and just copies
-; all characters into the buffer. This has to be changed for a vsnprintf like
-; function but is ok for now.
-; For simplicity, we will use memcpy to copy the stuff and will just rearrange
-; the stack to create a matching frame for memcpy.
-
-out:	ldy    	#4     	       	 	; d on stack
-	lda	(sp),y
-	sta	ptr1
-	iny
-	lda	(sp),y
-	sta	ptr1+1	       	 	; Save d into ptr1
-
-; Get a pointer to the target buffer and store it into the stack frame
-; currently occupied by d
-
-	dey	  	       	 	; d->ptr
-	lda	(ptr1),y       	 	; Low byte of d->ptr
-	ldy	#0
-	add	(ptr1),y       	 	; Low byte of d->ccount
-	ldy	#4
-	sta	(sp),y	       	 	; Store into d stackframe
-	iny
-	lda	(ptr1),y       	 	; High byte of d->ptr
-	ldy	#1
-	adc	(ptr1),y       	 	; High byte of d->ccount
-	ldy	#5
-	sta	(sp),y
-
-; Increment the total count by the number if bytes in this chunk. While doing
-; so, load count into a/x since _memcpy is a fastcall function
-
-	jsr	popax		 	; Get count
-	pha	  		 	; Save low byte
-	ldy	#0
-       	add	(ptr1),y	 	; Low byte of d->ccount
-	sta	(ptr1),y
-	iny
-	txa	  		 	; High byte of count
-	adc	(ptr1),y	 	; High byte of d->ccount
-	sta	(ptr1),y
-	pla	  		 	; Restore low byte of count
-
-; We have the correct stackframe for memcpy now, call it
-
-	jmp	_memcpy
+	.import	      	ldax0sp, pushax, staxysp
+	.import	      	_vsnprintf
 
 
 ; ----------------------------------------------------------------------------
 ; vsprintf - formatted output into a buffer
 ;
-; int vsprintf (char* buf, const char* format, va_list ap)
-; {
-;     struct outdesc d;
-;
-;     /* Setup descriptor */
-;     d.fout = out;
-;     d.ptr  = buf;
-;     d.uns  = 0x7FFF;
-;
-;     /* Do formatting and output */
-;     _printf (&d, format, ap);
-;
-;     /* Terminate the result string */
-;     buf [d.ccount++] = '\0';
+; int vsprintf (char* buf, const char* format, va_list ap);
 ;
-;     /* Return bytes written */
-;     return d.ccount;
-; }
 
 
 _vsprintf:
 	pha	  		; Save low byte of ap
+        txa
+        pha                     ; Save high byte of op
 
-; Setup the outdesc structure
-
-	lda	#0
-	sta	outdesc
-	sta	outdesc+1	; Clear ccount
-
-; Reorder the stack. Replace buf 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 buf
-	sta	outdesc+4	; Store into outdesc.ptr
-	lda	#<outdesc
-	sta	(sp),y
-	iny
-	lda	(sp),y	 	; High byte of buf
-	sta	outdesc+5
-	lda	#>outdesc
-	sta	(sp),y
-
-; Restore low byte of ap and call _printf
-
-	pla
-	jsr	__printf
-
-; Terminate the string
-
-	lda	outdesc+4	; buf
-	add	outdesc+0	; +ccount
-	sta	ptr1
-	lda	outdesc+5
-	adc	outdesc+1
-	sta	ptr1+1
-	ldy	#0
-	tya
-	sta	(ptr1),y
+; Build a stackframe for vsnprintf. To do that, we move format one word down,
+; and store 0x7FF (INT_MAX) as size.
 
-; Return the number of bytes written.
+        jsr     ldax0sp         ; Get format
+        jsr     pushax          ; And push it
+        lda     #$7F
+        ldx     #$FF            ; INT_MAX
+        ldy     #2
+        jsr     staxysp
 
-        lda     outdesc         ; ccount
-        ldx     outdesc+1
-	rts
+; Retrieve ap and contine by jumping to _vsnprintf, which will cleanup the stack
 
+        pla
+        tax
+        pla
+        jmp     _vsnprintf
 
-- 
2.39.5