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Merged
boriel merged 2 commits into from
Oct 29, 2017
Merged

Bugfix/memcopy #102

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91cee4e
Merged in chore/example (pull request #109)
boriel Oct 27, 2017
4168200
bugfix: fix memcopy library function
boriel Oct 28, 2017
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9 changes: 5 additions & 4 deletions library-asm/memcopy.asm
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,7 @@
; ----------------------------------------------------------------

; Emulates both memmove and memcpy C routines
; Blocks will safely copies if they overlap
; Block will be safely copied if they overlap

; HL => Start of source block
; DE => Start of destiny block
Expand All @@ -19,15 +19,16 @@ __MEMCPY:
PROC
LOCAL __MEMCPY2

add hl, bc
push hl
add hl, bc ; addr of last source block byte + 1
or a
sbc hl, de ; checks if DE > HL + BC
add hl, de ; recovers HL. If Carry set => DE > HL
pop hl ; recovers HL. If carry => DE > HL + BC (no overlap)
jr c, __MEMCPY2

; Now checks if DE <= HL

sbc hl, de
sbc hl, de ; Even if overlap, if DE < HL then we can LDIR safely
add hl, de
jr nc, __MEMCPY2

Expand Down
56 changes: 41 additions & 15 deletions library/memcopy.bas
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Original file line number Diff line number Diff line change
Expand Up @@ -3,8 +3,6 @@
'
' Copyleft (k) 2008
' by Jose Rodriguez-Rosa (a.k.a. Boriel) <http://www.boriel.com>
'
' Use this file as a template to develop your own library file
' ----------------------------------------------------------------

#ifndef __LIBRARY_MEMCOPY__
Expand All @@ -13,20 +11,21 @@ REM Avoid recursive / multiple inclusion

#define __LIBRARY_MEMCOPY__

#define memmove memcopy

#pragma push(case_insensitive)
#pragma case_insensitive = True

' ----------------------------------------------------------------
' sub MEMCOPY(sourceaddr, destaddr, blocklength)
' Sub MemMove(sourceaddr, destaddr, blocklength)
'
' Parameters:
' souceaddr: memory address of source block to copy
' destaddr: memory address of destiny block to copy
' length: number of bytes to copy
'
' Copies block of memory from source to dest. Block may overlap
' Copies block of memory safely from source to dest.
' Source and destiny blocks may overlap
' ----------------------------------------------------------------
sub fastcall memcopy(source as uinteger, dest as uinteger, length as uinteger)
sub fastcall MemMove(source as uinteger, dest as uinteger, length as uinteger)
asm
; Emulates both memmove and memcpy C routines
; Blocks will safely copies if they overlap
Expand All @@ -35,22 +34,49 @@ sub fastcall memcopy(source as uinteger, dest as uinteger, length as uinteger)
; DE => Start of destiny block
; BC => Block length

exx
pop hl ; ret addr
exx

pop af ; ret addr
pop de ; dest
pop bc ; length

exx
push hl ; stores ret addr back
exx
push af ; stores ret addr back

jp __MEMCPY
end asm
end sub


' ----------------------------------------------------------------
' Sub MemCopy(sourceaddr, destaddr, blocklength)
'
' Parameters:
' souceaddr: memory address of source block to copy
' destaddr: memory address of destiny block to copy
' length: number of bytes to copy
'
' Copies block of memory from source to dest.
' Source and destiny blocks should not overlap.
' This sub is slighly faster than memmove
' ----------------------------------------------------------------
sub fastcall MemCopy(source as uinteger, dest as uinteger, length as uinteger)
asm
; Emulates both memmove and memcpy C routines
; Blocks will safely copies if they DON'T overlap

; HL => Start of source block
; DE => Start of destiny block
; BC => Block length

pop af ; ret addr
pop de ; dest
pop bc ; length
push af ; stores ret addr back
ldir
end asm
end sub


#require "memcopy.asm"

#pragma pop(case_insensitive)

#endif

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