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- ; vim: ts=4:et:sw=4:
- ; Copyleft (K) by Jose M. Rodriguez de la Rosa
- ; (a.k.a. Boriel)
- ; http://www.boriel.com
- ;
- ; This ASM library is licensed under the BSD license
- ; you can use it for any purpose (even for commercial
- ; closed source programs).
- ;
- ; Please read the BSD license on the internet
- ; ----- IMPLEMENTATION NOTES ------
- ; The heap is implemented as a linked list of free blocks.
- ; Each free block contains this info:
- ;
- ; +----------------+ <-- HEAP START
- ; | Size (2 bytes) |
- ; | 0 | <-- Size = 0 => DUMMY HEADER BLOCK
- ; +----------------+
- ; | Next (2 bytes) |---+
- ; +----------------+ <-+
- ; | Size (2 bytes) |
- ; +----------------+
- ; | Next (2 bytes) |---+
- ; +----------------+ |
- ; | <free bytes...>| | <-- If Size > 4, then this contains (size - 4) bytes
- ; | (0 if Size = 4)| |
- ; +----------------+ <-+
- ; | Size (2 bytes) |
- ; +----------------+
- ; | Next (2 bytes) |---+
- ; +----------------+ |
- ; | <free bytes...>| |
- ; | (0 if Size = 4)| |
- ; +----------------+ |
- ; <Allocated> | <-- This zone is in use (Already allocated)
- ; +----------------+ <-+
- ; | Size (2 bytes) |
- ; +----------------+
- ; | Next (2 bytes) |---+
- ; +----------------+ |
- ; | <free bytes...>| |
- ; | (0 if Size = 4)| |
- ; +----------------+ <-+
- ; | Next (2 bytes) |--> NULL => END OF LIST
- ; | 0 = NULL |
- ; +----------------+
- ; | <free bytes...>|
- ; | (0 if Size = 4)|
- ; +----------------+
- ; When a block is FREED, the previous and next pointers are examined to see
- ; if we can defragment the heap. If the block to be breed is just next to the
- ; previous, or to the next (or both) they will be converted into a single
- ; block (so defragmented).
- ; MEMORY MANAGER
- ;
- ; This library must be initialized calling __MEM_INIT with
- ; HL = BLOCK Start & DE = Length.
- ; An init directive is useful for initialization routines.
- ; They will be added automatically if needed.
- #include once <error.asm>
- #include once <alloc.asm>
- #include once <free.asm>
- ; ---------------------------------------------------------------------
- ; MEM_REALLOC
- ; Reallocates a block of memory in the heap.
- ;
- ; Parameters
- ; HL = Pointer to the original block
- ; BC = New Length of requested memory block
- ;
- ; Returns:
- ; HL = Pointer to the allocated block in memory. Returns 0 (NULL)
- ; if the block could not be allocated (out of memory)
- ;
- ; Notes:
- ; If BC = 0, the block is freed, otherwise
- ; the content of the original block is copied to the new one, and
- ; the new size is adjusted. If BC < original length, the content
- ; will be truncated. Otherwise, extra block content might contain
- ; memory garbage.
- ;
- ; ---------------------------------------------------------------------
- __REALLOC:
- ; Reallocates block pointed by HL, with new length BC
- ;- PROC
- ;- LOCAL __REALLOC_END
- lda z80_h ;- ld a,h
- sta z80_a
- ora z80_l ;- or l
- jeq __MEM_ALLOC ;- jp z, __MEM_ALLOC ; If HL == NULL, just do a malloc
- ldy #$00 ;- ld e,(hl)
- lda (z80_hl),y
- sta z80_e
- inc z80_l ;- inc hl
- bne *+4
- inc z80_h
- ldy #$00 ;- ld d, (hl) ; DE = First 2 bytes of HL block
- lda (z80_hl),y
- sta z80_d
- lda z80_l ;- push hl
- pha
- lda z80_h
- pha
- lda z80_c ;- exx
- ldx z80_cp
- stx z80_c
- sta z80_cp
- lda z80_b
- ldx z80_bp
- stx z80_b
- sta z80_bp
- lda z80_e
- ldx z80_ep
- stx z80_e
- sta z80_ep
- lda z80_d
- ldx z80_dp
- stx z80_d
- sta z80_dp
- lda z80_l
- ldx z80_lp
- stx z80_l
- sta z80_lp
- lda z80_h
- ldx z80_hp
- stx z80_h
- sta z80_hp
- pla ;- pop de
- sta z80_d
- pla
- sta z80_e
- inc z80_e ;- inc de ; DE' <- HL + 2
- bne *+4
- inc z80_d
- lda z80_c ;- exx ; DE' <- HL (Saves current pointer into DE')
- ldx z80_cp
- stx z80_c
- sta z80_cp
- lda z80_b
- ldx z80_bp
- stx z80_b
- sta z80_bp
- lda z80_e
- ldx z80_ep
- stx z80_e
- sta z80_ep
- lda z80_d
- ldx z80_dp
- stx z80_d
- sta z80_dp
- lda z80_l
- ldx z80_lp
- stx z80_l
- sta z80_lp
- lda z80_h
- ldx z80_hp
- stx z80_h
- sta z80_hp
- ;- dec hl ; HL = Block start
- lda z80_e ;- push de
- pha
- lda z80_d
- pha
- lda z80_c ;- push bc
- pha
- lda z80_b
- pha
- jsr __MEM_FREE ;- call __MEM_FREE ; Frees current block
- pla ;- pop bc
- sta z80_b
- pla
- sta z80_c
- lda z80_c ;- push bc
- pha
- lda z80_b
- pha
- jsr __MEM_ALLOC ;- call __MEM_ALLOC ; Gets a new block of length BC
- pla ;- pop bc
- sta z80_b
- pla
- sta z80_c
- pla ;- pop de
- sta z80_d
- pla
- sta z80_e
- lda z80_h ;- ld a,h
- sta z80_a
- ora z80_l ;- or l
- ;- ret z ; Return if HL == NULL (No memory)
- lda z80_e ;- ld (hl),e
- ldy #$00
- sta (z80_hl),y
- inc z80_l ;- inc hl
- bne *+4
- inc z80_h
- lda z80_d ;- ld (hl),d
- ldy #$00
- sta (z80_hl),y
- inc z80_l ;- inc hl ; Recovers first 2 bytes in HL
- bne *+4
- inc z80_h
- ;- dec bc
- ;- dec bc ; BC = BC - 2 (Two bytes copied)
- lda z80_b ;- ld a,b
- sta z80_a
- ora z80_c ;- or c
- ;- jp z, __REALLOC_END ; Ret if nothing to copy (BC == 0)
- lda z80_c ;- exx
- ldx z80_cp
- stx z80_c
- sta z80_cp
- lda z80_b
- ldx z80_bp
- stx z80_b
- sta z80_bp
- lda z80_e
- ldx z80_ep
- stx z80_e
- sta z80_ep
- lda z80_d
- ldx z80_dp
- stx z80_d
- sta z80_dp
- lda z80_l
- ldx z80_lp
- stx z80_l
- sta z80_lp
- lda z80_h
- ldx z80_hp
- stx z80_h
- sta z80_hp
- lda z80_e ;- push de
- pha
- lda z80_d
- pha
- lda z80_c ;- exx
- ldx z80_cp
- stx z80_c
- sta z80_cp
- lda z80_b
- ldx z80_bp
- stx z80_b
- sta z80_bp
- lda z80_e
- ldx z80_ep
- stx z80_e
- sta z80_ep
- lda z80_d
- ldx z80_dp
- stx z80_d
- sta z80_dp
- lda z80_l
- ldx z80_lp
- stx z80_l
- sta z80_lp
- lda z80_h
- ldx z80_hp
- stx z80_h
- sta z80_hp
- pla ;- pop de ; DE <- DE' ; Start of remaining block
- sta z80_d
- pla
- sta z80_e
- lda z80_l ;- push hl ; Saves current Block + 2 start
- pha
- lda z80_h
- pha
- lda z80_e ;- ex de,hl ; Exchanges them: DE is destiny block
- ldx z80_l
- stx z80_e
- sta z80_l
- lda z80_d
- ldx z80_h
- stx z80_d
- sta z80_h
- ;- ldir ; Copies BC Bytes
- pla ;- pop hl ; Recovers Block + 2 start
- sta z80_h
- pla
- sta z80_l
- __REALLOC_END:
- ;- dec hl ; Set HL
- ;- dec hl ; To begin of block
- rts ;- ret
- ;- ENDP
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