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mem.asm
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;===================================================================================================
; Memory Allocations
;
; Written By: Oded Cnaan ([email protected])
; Site: http://odedc.net
; Licence: GPLv3 (see LICENSE file)
; Package: XXX
;
; Description:
; Allows allocating and freeing memory on RAM
;===================================================================================================
LOCALS @@
DATASEG
MAX_MALLOC_SEGS equ 50
_programMemFreed db FALSE
_allocatedSegments dw MAX_MALLOC_SEGS dup(0)
_allocatedSegmentsIndex dw 0
CODESEG
;+-+-+-+-+-+-+-+-+ HEAP MNGM. +-+-+-+-+-+-+-+-++-+-+-+-+-+
; Before allocating new memory on the heap,
; call HeapFreeUnused
;
; since When DOS executes a program,
; it gives all of the available memory, from the start of that
; program to the end of RAM, to the executing process.
; Any attempt to allocate memory without first giving unused
; memory back to the system will produce an “insufficient
; memory” error.
;
; This PROC should be called before allocating memory
;
; call HeapReset
;----------------------------------------------------------
PROC FreeProgramMem
store_sp_bp
mov dx,ss ; Stack segment
mov bx,256 / 16 + 1 ; stack size in paragraphs
add bx,dx ; BX = end
mov ax,es ; ES = PSP (start)
sub bx,ax ; BX = new size in paragraphs
mov ah,4Ah
int 21h
mov [_programMemFreed], TRUE
restore_sp_bp
ret
ENDP FreeProgramMem
;----------------------------------------------------------
; Allocate memory on the heap
;
; push size (in paragraphs) (2000h = 128 KB)
; call malloc
;
; Parag = bytes / 16
;
; Return value:
; AX = segment address of allocated memory block (MCB + 1para)
; 0 on error
; BX = size in paras of the largest block of memory available
; 0 on error
; CF = 0 if successful
; = 1 if error
; Allocated memory is at AX:0000
;----------------------------------------------------------
PROC malloc
store_sp_bp
push cx di
cmp [_programMemFreed], TRUE
jne @@error
clc
mov bx, [word bp+4]
mov ah, 48h
int 21h
jc @@error
mov cx, [_allocatedSegmentsIndex] ; cx = index
shl cx, 1 ; index * 2 (counts words)
mov di, offset _allocatedSegments
add di, cx
mov [di], ax ; save allocated segment
inc [_allocatedSegmentsIndex] ; increment index
jmp @@ok
@@error:
mov ax,0
mov bx,0
@@ok:
pop di cx
restore_sp_bp
ret 2
ENDP malloc
;----------------------------------------------------------
; Free memory on the heap
;
; push addr (address of block)
; call mfree
;
; Return value: ax register is a pointer to the memory
; or 0 on error
;----------------------------------------------------------
PROC mfree
store_sp_bp
push es
; now the stack is
; bp+0 => old base pointer
; bp+2 => return address
; bp+4 => addr
; saved registers
;{
addr_ equ [word bp+4]
;}
push addr_
pop es
mov ah, 49h
int 21h
pop es
restore_sp_bp
ret 2
ENDP mfree
;----------------------------------------------------------
; Free all allocated segments on the heap
;
; call mfreeAll
;
; Return value: ax register is a pointer to the memory
; or 0 on error
;----------------------------------------------------------
PROC mfreeAll
store_sp_bp
sub sp,2
push es cx bx
; now the stack is
; bp-2=> index
; bp+0 => old base pointer
; bp+2 => return address
; saved registers
;{
index_ equ [word bp-2]
;}
mov index_, 0
mov cx, [_allocatedSegmentsIndex]
cmp cx, 0
je @@ok ; nothing to release
@@fr:
mov bx, index_
shr bx,1 ; index * 2 (counts in words)
add bx, offset _allocatedSegments
push [word bx]
pop es ; es = segment
mov ah, 49h
int 21h ; free
inc index_ ; index++
loop @@fr
@@ok:
pop bx cx es
restore_sp_bp
ret
ENDP mfreeAll
;----------------------------------------------------------
; Copies memory from one address to another
;
; push from address
; push from seg
; push to address
; push to seg
; push length in bytes
; call MemCpy
;----------------------------------------------------------
PROC MemCpy
store_sp_bp
push ax
push cx
push di
push si
push ds
push es
; now the stack is
; bp+0 => old base pointer
; bp+2 => return address
; bp+4 => length
; bp+6 => to seg
; bp+8 => to addr
; bp+10 => from seg
; bp+12 => from addr
; saved registers
mov si, [WORD bp+12] ; from
mov ds, [WORD bp+10] ; from seg
mov di, [WORD bp+8] ; to
mov es, [WORD bp+6] ; to seg
; ds:si => es:di
mov cx, [WORD bp+4] ; length
cld
rep movsb
pop es
pop ds
pop si
pop di
pop cx
pop ax
restore_sp_bp
ret 10
ENDP MemCpy
;----------------------------------------------------------
;
;----------------------------------------------------------
MACRO translate_coord_to_addr reg, mem_w, x, y
push ax
push bx
push cx
mov ax, [WORD y]
mov bx, [WORD mem_w]
mul bx
mov cx, ax
add cx, [WORD x]
mov reg, cx
pop cx
pop bx
pop ax
ENDM
;----------------------------------------------------------
; Copies memscreen area from screen address (seg es) to
; another memory
;
; push video segment
; push x1
; push y1
; push x2
; push y2
; push to address
; push to seg
; push mem width
; call ScreenCpy
;----------------------------------------------------------
PROC ScreenCpyFrom
store_sp_bp
sub sp,4
push ax
push cx
push di
push si
push ds
push es
; now the stack is
; bp-4 => x
; bp-2 => y
; bp+0 => old base pointer
; bp+2 => return address
; bp+4 => mem w
; bp+6 => to seg
; bp+8 => to addr
; bp+10 => y2
; bp+12 => x2
; bp+14 => y1
; bp+16 => x1
; bp+18 => video seg
; saved registers
mov ds, [WORD bp+6] ; target seg
mov es, [WORD bp+18] ; source video seg
@@rect__rect:
push [word bp+14] ; y1
pop [word bp-2] ; y = y1
@@rect__v:
push [word bp+16] ; x1
pop [word bp-4] ; x = x1
@@rect__h:
translate_coord_to_addr di, 320, bp-4, bp-2 ; source addr
translate_coord_to_addr si, bp+4, bp+18, bp+16 ; target addr
push [WORD es:di]
pop [WORD ds:si]
;gr_set_pixel [bp-4], [bp-2], [gr_pen_color] ; draw pixel at (x1,y1)
inc [word bp-4] ; x1++
cmpv [bp-4], [bp+12], ax
jl @@rect__h ; if (x1 < x2) goto GR_draw_rect__h
inc [word bp-2] ; y++
cmpv [bp-2], [bp+10], ax
jl @@rect__v ; if (y1 < y2) goto GR_draw_rect__v
pop es
pop ds
pop si
pop di
pop cx
pop ax
restore_sp_bp
ret 16
ENDP ScreenCpyFrom
;----------------------------------------------------------
; Copies memscreen area from screen address (seg es) to
; another memory
;
; push video segment
; push x1
; push y1
; push x2
; push y2
; push from address
; push from seg
; push mem width
; call ScreenCpy
;----------------------------------------------------------
PROC ScreenCpyTo
store_sp_bp
sub sp,4
push ax
push cx
push di
push si
push ds
push es
; now the stack is
; bp-4 => x
; bp-2 => y
; bp+0 => old base pointer
; bp+2 => return address
; bp+4 => mem w
; bp+6 => to seg
; bp+8 => to addr
; bp+10 => y2
; bp+12 => x2
; bp+14 => y1
; bp+16 => x1
; bp+18 => video seg
; saved registers
mov ds, [WORD bp+6] ; target seg
mov es, [WORD bp+18] ; source video seg
xor ax,ax
@@rect__rect:
push [word bp+14] ; y1
pop [word bp-2] ; y = y1
@@rect__v:
push [word bp+16] ; x1
pop [word bp-4] ; x = x1
@@rect__h:
translate_coord_to_addr di, 320, bp-4, bp-2 ; target addr
translate_coord_to_addr si, bp+4, bp-4, bp-2 ; source addr
mov al, [BYTE ds:si]
mov [byte es:di],al
;gr_set_pixel [bp-4], [bp-2], [gr_pen_color] ; draw pixel at (x1,y1)
inc [word bp-4] ; x1++
cmpv [bp-4], [bp+12], ax
jl @@rect__h ; if (x1 < x2) goto GR_draw_rect__h
inc [word bp-2] ; y++
cmpv [bp-2], [bp+10], ax
jl @@rect__v ; if (y1 < y2) goto GR_draw_rect__v
pop es
pop ds
pop si
pop di
pop cx
pop ax
restore_sp_bp
ret 16
ENDP ScreenCpyTo
;----------------------------------------------------------
; Sets the content of the memory addressed by
; Param1:Param2 for N bytes to the given value
;
; push 10 ; length in bytes
; push ds ; segment
; push offset mem ; offset
; push value
; call SetMemByte
;----------------------------------------------------------
PROC SetMemByte
store_sp_bp
push ax
push bx
push cx
push es
; now the stack is
; bp+0 => old base pointer
; bp+2 => return address
; bp+4 => param4 (value)
; bp+6 => param3 (offset)
; bp+8 => param2 (seg)
; bp+10 => param1 (length)
; saved registers
mov cx, [WORD bp+4] ; value
mov ax, [WORD bp+10] ; length
test ax,ax ; See if the requested length is zero
js @@ZeroMemBEP ; Jump to the end of the procedure if yes
mov bx,[WORD PTR BP+6] ; BX is now equal to the requested offset
mov es,[WORD PTR BP+8] ; ES is now equal to the requested segment
@@ZeroMemBLoop:
mov [BYTE PTR ES:BX] , cl ; Move one byte to ES:[BX]
inc bx
dec ax ; Decrement the counter
jne @@ZeroMemBLoop
pop es
pop cx
pop bx
pop ax
@@ZeroMemBEP:
restore_sp_bp
ret 8
ENDP SetMemByte
;----------------------------------------------------------
; Sets the content of the memory addressed by
; Param1:Param2 for N words to the given value
;
; push 10 ; length in words
; push ds ; segment
; push offset mem ; offset
; push value
; call SetMemWord
;----------------------------------------------------------
PROC SetMemWord
store_sp_bp
push ax
push bx
push cx
push es
; now the stack is
; bp+0 => old base pointer
; bp+2 => return address
; bp+4 => param4 (value)
; bp+6 => param3 (offset)
; bp+8 => param2 (seg)
; bp+10 => param1 (length)
; saved registers
mov cx, [WORD bp+4] ; value
mov ax, [word bp+10] ; length
test ax,ax ; See if the requested length is zero
js @@ZeroMemWEP ; Jump to the end of the procedure if yes
mov bx,[WORD PTR BP+6] ; BX is now equal to the requested offset
mov es,[WORD PTR BP+8] ; ES is now equal to the requested segment
@@ZeroMemWLoop:
mov [WORD PTR ES:BX] , cx ; Move one word to ES:[BX]
add bx,2
dec ax ; Decrement the counter
jne @@ZeroMemWLoop
pop es
pop cx
pop bx
pop ax
@@ZeroMemWEP:
restore_sp_bp
ret 8
ENDP SetMemWord