mirror of https://github.com/cc65/cc65.git
105 lines
3.1 KiB
ArmAsm
105 lines
3.1 KiB
ArmAsm
;
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; This file, instead of "common/memcpy.s", will be assembled for the pce
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; target. This version is smaller and faster because it uses the HuC6280's
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; block-copy instructions.
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;
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; 2003-08-20, Ullrich von Bassewitz
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; 2015-11-02, Greg King
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;
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; void* __fastcall__ memcpy (void* dest, const void* src, size_t size);
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;
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; NOTE: This function contains entry points for memmove(), which resorts to
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; memcpy() for incrementing copies. The PC-Engine memset() uses this memcpy()
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; to fill memory quickly. Don't change this module without looking at
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; "pce/memmove.s" and "pce/memset.s"!
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;
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.export _memcpy
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.export memcpy_increment, memcpy_transfer, memcpy_getparams
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.import incsp2, popax, popptr1
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.importzp sp, ptr1, ptr2, ptr3
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; The structure of the transfer instructions
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.struct
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opcode .byte
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source .addr
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destination .addr
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length .word
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.endstruct
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; ----------------------------------------------------------------------
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_memcpy:
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jsr memcpy_getparams
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memcpy_increment:
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ldy #$73 ; TII opcode
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memcpy_transfer:
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sty transfer + opcode
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lda ptr1
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ldx ptr1+1
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sta transfer + source
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stx transfer + source+1
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lda ptr2
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ldx ptr2+1
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sta transfer + destination
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stx transfer + destination+1
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lda ptr3
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ldx ptr3+1
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sta transfer + length
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stx transfer + length+1
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jmp transfer
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; ----------------------------------------------------------------------
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; Get the parameters from the stack, as follows:
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;
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; size --> ptr3
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; src --> ptr1
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; dest --> ptr2
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;
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; The first argument (dest) will remain on the stack; and, is returned in .XA!
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memcpy_getparams:
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sta ptr3
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stx ptr3+1 ; save size
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ora ptr3+1
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bne @L1
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; The size is zero; copy nothing; just return the dest address.
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; (The HuC6280's transfer instructions can't copy $0000 bytes;
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; they would copy $10000 [64K] bytes instead.)
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ply ; drop return address
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plx
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jsr incsp2 ; drop src address
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jmp popax ; get pointer; return it as result
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@L1: jsr popptr1 ; save src
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; (Direct stack access is six cycles faster [total cycle count].)
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iny ; (Y=0 by popptr1, need '1' here) save dest
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lda (sp),y ; get high byte
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tax
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lda (sp) ; get low byte
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sta ptr2
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stx ptr2+1
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rts ; return dest address (for memmove)
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; ----------------------------------------------------------------------
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; The transfer instructions use inline arguments.
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; Therefore, we must build the instruction in the DATA segment.
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.data
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transfer:
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tii $FFFF, $FFFF, $0001
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jmp popax ; get pointer; return it as result
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