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123 lines
3.1 KiB
NASM
123 lines
3.1 KiB
NASM
4 years ago
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; CALL FRESPACE(AH,AL,BH,BL,CH,CL). CL SHOULD BE 0 for default
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; drive 1 for A, 2 for B, 3 for C, etc. The value of the
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; other variables does not matter. They will come back
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; with a meaningful value.
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;
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; AN EXAMPLE PROGRAM:
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;
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; 10 defint a-z
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; 20 color 7,1:cls
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; 30 test1=1:ah=0:al=0:bh=0:ch=0:cl=1:test2=2
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; 35 INPUT"DRIVE 0=DEFAULT, 1=A, 2=B, 3=C";CL
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; 37 PRINT"JUST BEFORE CALL"
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; 40 CALL FRESPACE(AH,AL,BH,BL,CH,CL)
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; 45 PRINT"JUST AFTER CALL"
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; 50 PRINT" AH=";AH;" AL=";AL;" BH=";BH;" BL=";BL;" CH=";CH;" CL=";CL;
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; 60 UFREE!=256*AH+AL
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; 70 UBYTES!=256*BH+BL
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; 80 USECTOR!=256*CH+CL
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; 90 PRINT"UFREE!=";UFREE!;" UBYTES!=";UBYTES!;" USECTOR!=";USECTOR!
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; 100 FRESPACE!=UFREE!*UBYTES!*USECTOR!
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; 110 PRINT"FRESPACE!=";FRESPACE!
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; 120 PRINT"THIS SHOULD BE 1",TEST1
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; 130 PRINT"THIS SHOULD BE 2",TEST2
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;
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get_spa equ 36h ;Get disk free space function call
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doscall equ 21h ;DOS interrupt number
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dgroup group datarea
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datarea segment para public 'DATA'
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ah_ret dw ? ;ah to be sent back
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al_ret dw ? ;al to be sent back
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bh_ret dw ? ;bh to be sent back
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bl_ret dw ? ;bl to be sent back
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ch_ret dw ? ;ch to be sent back
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cl_ret dw ? ;cl to be sent back
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datarea ENDS
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;
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cseg segment 'CODE'
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assume cs:cseg
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public frespace
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frespace proc far
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push bp ;BP from BASIC
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mov bp,sp ;set base for parm list
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push ds ;DS from basic work area
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push es ;ES from basic work area
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mov ax,datarea ;establish data addressability
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mov ds,ax ;now DS is local data
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assume ds:datarea
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;
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;
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;
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;
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push bp
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sub ax,ax
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mov si,ss:[bp+6] ;get addr of parameter
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mov al,es:[si] ;get value of parm
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mov dx,ax ;dl contains the drive number on call
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;dh will be zero
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mov ah,get_spa ;get space function number
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int doscall ;Call DOS
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; Move the values into local work area to prepare to send back to basic
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xchg dx,ax ;must have a word. Want to zero out DH.
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sub ax,ax ; produce the zero
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xchg dx,ax ; DX is now zero.
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; DH is what we really want as zero.
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mov dl,ah ;want to send back a byte
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mov ah_ret,dx ; prepare to return ah
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mov dl,al ;want to send back a byte
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mov al_ret,dx ; prepare to return al
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mov dl,bh ;want to send back a byte
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mov bh_ret,dx ; prepare to return bh
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mov dl,bl ;want to send back a byte
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mov bl_ret,dx ; prepare to return bl
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mov dl,ch ;want to send back a byte
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mov ch_ret,dx ; prepare to return ch
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mov dl,cl ;want to send back a byte
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mov cl_ret,dx ; prepare to return cl
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; Go back
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pop bp ;get back Basic's workspace
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mov ax,cl_ret
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mov si,ss:[bp+6]
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mov es:[si],ax ;return cl
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mov ax,ch_ret
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mov si,ss:[bp+8]
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mov es:[si],ax ;return ch
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mov ax,bl_ret
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mov si,ss:[bp+10]
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mov es:[si],ax ;return bl
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mov ax,bh_ret
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mov si,ss:[bp+12]
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mov es:[si],ax ;return bh
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mov ax,al_ret
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mov si,ss:[bp+14]
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mov es:[si],ax ;return al
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mov ax,ah_ret
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mov si,ss:[bp+16]
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mov es:[si],ax ;return ah
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;
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pop es
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pop ds
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pop bp
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ret 12 ;return to basic 6 parameters were sent
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frespace endp
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;-----------------------------------------------------------------------
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cseg ends
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end ;end for assembler
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