meep-eep
e7eabd46b9
git-svn-id: svn://svn.code.sf.net/p/sc2/code/trunk@1545 8092fc87-c524-0410-9efc-e669fe64eaf9
102 lines
2.3 KiB
NASM
102 lines
2.3 KiB
NASM
;-----------------------------------------------------------------
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; dalloc.asm
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; ----------
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; Memory-allocation routines that operate OUTSIDE of the data segment.
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; These work with SEGMENT addresses, NOT actual pointers.
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; For allocation in the data segment, just use malloc () and free ().
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;-----------------------------------------------------------------
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include asm.inc
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HEADER dalloc
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PSEG dalloc
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;-----------------------------------------------------------------
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; WORD DAlloc (size);
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; UWORD size;
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; Allocate a block of "size" bytes and return its segment. If
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; the allocation fails, return NULL.
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; Since this uses DOS allocation, it will allocate just enough paragraphs
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; for the number of bytes requested.
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;-----------------------------------------------------------------
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public _DAlloc
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STARTPROC _DAlloc
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push bp
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mov bp,sp
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mov ah,048h ; function #
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; bx = number of paragraphs = (bytes >> 4) + (bytes & 0x0f) ? 1 : 0;
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mov bx,ARGB[bp]
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mov cl,4
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shr bx,cl
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test word ptr ARGB[bp],0fh
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je dalloc_p0
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inc bx
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dalloc_p0:
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int 021h
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jnc dalloc_p1
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xor ax,ax ; alloc failed, so return NULL
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dalloc_p1:
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pop bp
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ret
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ENDPROC _DAlloc
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;-----------------------------------------------------------------
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; void SFree (seg);
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; Was "DFree", but PLink said that conflicted with "dfree".
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; Free the block at the given segment address.
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;
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; Okay to call with NULL, so safe to call on already freed segment
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; variables. That DOESN'T mean it is okay to maintain two DIFFERENT
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; segment variables, and try to free the same region twice through
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; two different variables! Also, it is up to the caller to NULL
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; his sgment variable when done. Maybe we should switch to a model
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; where caller passes ADDRESS of segment variable! [sss]
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; Always returns null, so can use to null a variable holding a
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; segment address:
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; "segname = SFree(segname);"
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;-----------------------------------------------------------------
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public _SFree
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STARTPROC _SFree
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push bp
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mov bp,sp
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push es
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; if (!seg), don't do anything
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test word ptr ARGB[bp],0ffffh
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jz dfree_done
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; free the segment
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mov ah,049h
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mov es,ARGB[bp]
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int 021h
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ifdef DEBUGGING
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jnc dfree_1
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mov ax,9999
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push ax
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call _crash
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dfree_1:
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endif
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dfree_done:
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xor ax,ax ; NULL return value so can assign.
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pop es
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pop bp
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ret
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ENDPROC _SFree
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;-----------------------------------------------------------------
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ENDPS dalloc
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end
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