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Let vsprintf call vsnprintf to save code.

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git-svn-id: svn://svn.cc65.org/cc65/trunk@4247 b7a2c559-68d2-44c3-8de9-860c34a00d81
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uz 2009-09-27 12:18:06 +00:00
parent 067383eb6a
commit 5967b4845e
1 changed files with 19 additions and 140 deletions
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159
libsrc/common/vsprintf.s
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@ -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;
; int vsprintf (char* buf, const char* format, va_list ap);
;
; /* 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';
;
; /* Return bytes written */
; return d.ccount;
; }
_vsprintf:
pha ; Save low byte of ap
txa
pha ; Save high byte of op
; Setup the outdesc structure
; Build a stackframe for vsnprintf. To do that, we move format one word down,
; and store 0x7FF (INT_MAX) as size.
lda #0
sta outdesc
sta outdesc+1 ; Clear ccount
jsr ldax0sp ; Get format
jsr pushax ; And push it
lda #$7F
ldx #$FF ; INT_MAX
ldy #2
jsr staxysp
; 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
; Return the number of bytes written.
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