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70 lines
1.6 KiB
ArmAsm
70 lines
1.6 KiB
ArmAsm
;
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; int snprintf (char* buf, size_t size, const char* Format, ...);
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;
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; Ullrich von Bassewitz, 2009-09-26
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;
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.export _snprintf
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.import pushax, addysp, decsp6, _vsnprintf
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.importzp sp, ptr1
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.macpack generic
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; ----------------------------------------------------------------------------
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; Data
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.bss
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ParamSize: .res 1 ; Number of parameter bytes
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; ----------------------------------------------------------------------------
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; Code
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.code
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_snprintf:
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sty ParamSize ; Number of param bytes passed in Y
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; We have to push buf/size/format, both in the order they already have on stack.
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; To make this somewhat more efficient, we will create space on the stack and
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; then do a copy of the complete block instead of pushing each parameter
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; separately. Since the size of the arguments passed is the same as the size
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; of the fixed arguments, this will allow us to calculate the pointer to the
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; fixed size arguments easier (they're just ParamSize bytes away).
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jsr decsp6
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; Calculate a pointer to the Format argument
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lda ParamSize
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add sp
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sta ptr1
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ldx sp+1
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bcc @L1
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inx
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@L1: stx ptr1+1
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; Now copy buf/size/format
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ldy #6-1
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@L2: lda (ptr1),y
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sta (sp),y
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dey
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bpl @L2
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; Load va_list (last and __fastcall__ parameter to vsprintf)
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lda ptr1
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ldx ptr1+1
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; Call vsnprintf
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jsr _vsnprintf
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; Cleanup the stack. We will return what we got from vsprintf
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ldy ParamSize
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jmp addysp
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