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187 lines
3.9 KiB
ArmAsm
187 lines
3.9 KiB
ArmAsm
;
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; int vsnprintf (char* Buf, size_t size, const char* Format, va_list ap);
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;
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; Ullrich von Bassewitz, 2009-09-26
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;
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.export _vsnprintf
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.import ldaxysp, popax, incsp2, incsp6
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.import _memcpy, __printf
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.importzp sp, ptr1
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.macpack generic
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.data
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; ----------------------------------------------------------------------------
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;
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; Static data for the _vsnprintf routine
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;
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outdesc: ; Static outdesc structure
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.word 0 ; ccount
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.word out ; Output function pointer
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.word 0 ; ptr
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.word 0 ; Buffer size
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.code
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; ----------------------------------------------------------------------------
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; Callback routine used for the actual output.
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;
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; static void out (struct outdesc* d, const char* buf, unsigned count)
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; /* Routine used for writing */
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;
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; Since we know, we're called with a pointer to our static outdesc structure,
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; we don't need the pointer passed on the stack.
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out:
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; Calculate the space left in the buffer. If no space is left, don't copy
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; any characters
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lda outdesc+6 ; Low byte of buffer size
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sec
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sbc outdesc+0 ; Low byte of bytes already written
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sta ptr1
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lda outdesc+7
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sbc outdesc+1
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sta ptr1+1
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bcs @L0 ; Space left
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lda #0
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sta ptr1
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sta ptr1+1
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; Replace the pointer to d by a pointer to the write position in the buffer
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; for the call to memcpy that follows.
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@L0: lda outdesc+0
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clc
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adc outdesc+4
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ldy #4
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sta (sp),y
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lda outdesc+1
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adc outdesc+5
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iny
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sta (sp),y
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; Get Count from stack
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jsr popax
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; outdesc.ccount += Count;
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pha
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clc
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adc outdesc+0
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sta outdesc+0
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txa
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adc outdesc+1
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sta outdesc+1
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pla
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; if (Count > Left) Count = Left;
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cmp ptr1
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bne @L1
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cpx ptr1+1
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@L1: bcs @L2
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lda ptr1
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ldx ptr1+1
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; Jump to memcpy, which will cleanup the stack and return to the caller
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@L2: jmp _memcpy
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; ----------------------------------------------------------------------------
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; vsprintf - formatted output into a buffer
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;
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; int __fastcall__ vsnprintf (char* buf, size_t size, const char* format, va_list ap);
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;
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_vsnprintf:
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pha ; Save low byte of ap
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; Setup the outdesc structure
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lda #0
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sta outdesc
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sta outdesc+1 ; Clear ccount
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; Get the size parameter and replace it by a pointer to outdesc. This is to
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; build a stack frame for the call to _printf.
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; If size is zero, there's nothing to do.
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ldy #2
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lda (sp),y
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sta ptr1
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lda #<outdesc
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sta (sp),y
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iny
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lda (sp),y
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sta ptr1+1
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ora ptr1
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beq L9
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lda #>outdesc
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sta (sp),y
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; Write size-1 to the outdesc structure
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ldx ptr1
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ldy ptr1+1
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dex
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bne L1
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dey
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L1: stx outdesc+6
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sty outdesc+7
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; Copy buf to the outdesc structure
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ldy #5
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jsr ldaxysp
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sta outdesc+4
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stx outdesc+5
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; Restore low byte of ap and call _printf
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pla
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jsr __printf
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; Terminate the string
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lda outdesc+0
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ldx outdesc+1
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cpx outdesc+7
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bne L2
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cmp outdesc+6
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L2: bcc L3
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lda outdesc+6
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ldx outdesc+7
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clc
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L3: adc outdesc+4
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sta ptr1
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txa
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adc outdesc+5
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sta ptr1+1
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lda #0
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tay
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sta (ptr1),y
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; Return the number of bytes written and drop buf
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lda outdesc ; ccount
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ldx outdesc+1
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jmp incsp2
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; Bail out if size is zero
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L9: lda #0
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tax
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jmp incsp6 ; Drop parameters
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