mirror of https://github.com/cc65/cc65.git
189 lines
4.2 KiB
ArmAsm
189 lines
4.2 KiB
ArmAsm
;
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; int __fastcall__ vsscanf (const char* str, const char* format, va_list ap);
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; /* Standard C function */
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;
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; 2004-11-28, Ullrich von Bassewitz
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; 2014-09-10, Greg King
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;
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.export _vsscanf
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.import popax, __scanf
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.importzp sp, ptr1, ptr2
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.macpack generic
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; ----------------------------------------------------------------------------
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; Structure used to pass data to the callback functions
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.struct SSCANFDATA
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STR .addr
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INDEX .word
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.endstruct
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; ----------------------------------------------------------------------------
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; static int __fastcall__ get (struct sscanfdata* d)
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; /* Read a character from the input string and return it */
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; {
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; char C = d->str[d->index];
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; if (C == '\0') {
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; return EOF;
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; }
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; /* Increment index only if end not reached */
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; ++d->index;
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; return C;
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; }
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;
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.code
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.proc get
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sta ptr1
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stx ptr1+1 ; Save d
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; Get d->str adding the high byte of index to the pointer, so we can access
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; the byte in the string with just the low byte as index
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ldy #SSCANFDATA::STR
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lda (ptr1),y
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sta ptr2
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iny
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lda (ptr1),y
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ldy #SSCANFDATA::INDEX+1
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add (ptr1),y
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sta ptr2+1
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; Load the low byte of the index and fetch the byte from the string
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dey ; = SSCANFDATA::INDEX
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lda (ptr1),y
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tay
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lda (ptr2),y
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; Return EOF if we are at the end of the string
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bne L1
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lda #<-1
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tax
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rts
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; Bump the index (beware: A contains the char we must return)
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L1: tax ; Save return value
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tya ; Low byte of index
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ldy #SSCANFDATA::INDEX
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add #<$0001
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sta (ptr1),y
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iny
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lda (ptr1),y
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adc #>$0001
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sta (ptr1),y
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; Return the char just read
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txa
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ldx #>$0000
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rts
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.endproc
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; ----------------------------------------------------------------------------
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; static int __fastcall__ unget (int c, struct sscanfdata* d)
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; /* Push back a character onto the input stream */
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; {
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; /* We do assume here that the _scanf routine will not push back anything
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; ** not read, so we can ignore c safely and won't check the index.
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; */
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; --d->index;
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; return c;
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; }
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;
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.code
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.proc unget
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sta ptr1
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stx ptr1+1 ; Save d
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; Decrement the index
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ldy #SSCANFDATA::INDEX
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lda (ptr1),y
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sub #<$0001
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sta (ptr1),y
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iny
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lda (ptr1),y
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sbc #>$0001
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sta (ptr1),y
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; Return c
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jmp popax
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.endproc
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; ----------------------------------------------------------------------------
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; int __fastcall__ vsscanf (const char* str, const char* format, va_list ap)
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; /* Standard C function */
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; {
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; /* Initialize the data structs. The sscanfdata struct will be passed back
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; ** to the get and unget functions by _scanf().
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; */
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; static struct sscanfdata sd;
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; static const struct scanfdata d = {
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; ( getfunc) get,
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; (ungetfunc) unget,
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; (void*) &sd
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; };
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;
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; sd.str = str;
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; sd.index = 0;
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;
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; /* Call the internal function and return the result */
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; return _scanf (&d, format, ap);
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; }
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;
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.bss
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sd: .tag SSCANFDATA
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.rodata
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d: .addr get
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.addr unget
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.addr sd
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.code
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.proc _vsscanf
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; Save the low byte of ap (which is passed in a/x)
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pha
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; Initialize sd and at the same time replace str on the stack by a pointer
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; to d
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ldy #2 ; Stack offset of str
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lda (sp),y
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sta sd + SSCANFDATA::STR
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lda #<d
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sta (sp),y
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iny
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lda (sp),y
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sta sd + SSCANFDATA::STR+1
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lda #>d
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sta (sp),y
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lda #$00
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sta sd + SSCANFDATA::INDEX
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sta sd + SSCANFDATA::INDEX+1
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; Restore the low byte of ap, and jump to _scanf() which will clean up the stack
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pla
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jmp __scanf
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.endproc
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