Computer Select (Limited Edition)/Computer Select.iso/dobbs/v17n03/oopasm.exe/MATH.ASM

Assembly Source File | 1990-05-17 | 3.9 KB | 295 lines

    .MODEL    SMALL

    INCLUDE    equates.inc

    .CODE

COMMENT    %
==============================================================================
Convert long integer to string.

Passed:    dx,ax - long integer
    es:di - points to area for string

=============================================================================%
    PUBLIC  longToString
longToString    PROC      NEAR
    push        bp
    push        di
    push        es
    mov        bp,sp

    mov        si,dx
    test        dh,80h
    jz        lts1
    not        dx
    neg        ax
    sbb        dx,-1

lts1:    sub        bx,bx
    push        bx

lts2:    push        si
    push        dx
    push        ax
    mov        cx,0
    mov        bx,10
    call        lDiv
    pop        bx
    pop        cx

    push        dx
    push        ax
    push        cx
    push        bx
    mov        cx,0
    mov        bx,10
    call        lMul
    mov        cx,dx
    mov        bx,ax
    pop        ax
    pop        dx
    call        lSub
    mov        bx,ax
    pop        ax
    pop        dx
    pop        si
    add        bl,'0'
    push        bx
    mov        bx,ax
    or        bx,dx
    jnz        lts2

    mov        di,[bp][2]
    mov        es,[bp]
    cld
    test        si,8000h
    jz        lts3
    mov        al,'-'
    stosb

lts3:    pop        ax
    stosb
    or         al,al
    jnz        lts3
    mov        sp,bp
    pop        es
    pop        di
    pop        bp
    ret
longToString    ENDP



COMMENT    %
==============================================================================
Subtracts a long integer from a long integer.

Passed:    cx:bx - Number to be subtracted
    dx:ax - Number its subtracted from

Passes:    dx:ax - Result

=============================================================================%
lSub    PROC    NEAR
    push        ax
    mov        ax,0
    sub        ax,bx
    mov        bx,ax
    mov        ax,0
    sbb        ax,cx
    mov        cx,ax
    pop        ax
    add        ax,bx
    adc        dx,cx
    ret
lSub    ENDP




COMMENT    %
==============================================================================
Long integer multiplier.

=============================================================================%
lMul    PROC    NEAR
    push        si
    push        di
    push        bp
    sub        bp,bp

    test        dh,80h
    jz        lml1
    not        bp
    mov        si,0
    sub        si,ax
    mov        ax,si
    mov        si,0
    sbb        si,dx
    mov        dx,si

lml1:    test        Ch,80h
    jz        lml2
    not        bp
    mov        si,0
    sub        si,bx
    mov        bx,si
    mov        si,0
    sbb        si,cx
    mov        cx,si

lml2:    mov        si,dx
    mov        di,ax
    mul        bx
    push        ax
    push        dx

    mov        ax,si
    mul        bx
    pop        bx
    add        ax,bx
    adc        dx,0
    push        ax
    mov        bx,dx

    mov        ax,di
    mul        cx
    pop        di
    add        di,ax
    push        di
    mov        di,0
    adc        bx,dx
    adc        di,0

    mov        ax,si
    mul        cx
    add        ax,bx
    adc        dx,di
    pop        cx
    pop        bx

    or        ax,dx
    mov        ax,bx
    mov        dx,cx
    pushf
    test        bp,bp
    jz        lml3
    mov        bx,0
    sub        bx,ax
    mov        ax,bx
    mov        bx,0
    sbb        bx,dx
    mov        dx,bx

lml3:    popf
    pop        bp
    pop        di
    pop        si
    jz        lml4
    stc
lml4:    ret
lMul    ENDP




COMMENT    %
==============================================================================
Long integer divider.

=============================================================================%
lDiv    PROC    NEAR
    push        bp
    sub        sp,4
    mov        bp,sp
    mov        [bp],cx
    or        cx,bx
    jnz        ldv1
    sub        ax,ax
    mov        dx,ax
    jmp        ldv13

ldv1:    mov        [bp+2],dx
    or        dx,ax
    jnz        ldv2
    jmp        ldv13

ldv2:    mov        cx,[bp]
    mov        dx,[bp+2]
    mov        si,dx
    test        si,si
    jns        ldv3
    not        dx
    neg        ax
    sbb        dx,-1

ldv3:    xor        si,cx
    mov        [bp],si
    sub        si,si
    test        ch,ch
    jns        ldv4
    not        cx
    neg        bx
    sbb        cx,-1

ldv4:    jnz        ldv7
    test        bx,bx
    js        ldv7
    mov        di,20h

ldv5:    shl        ax,1
    rcl        dx,1
    rcl        si,1
    cmp        si,bx
    jb        ldv6
    sub        si,bx
    inc        ax

ldv6:    dec        di
    jnz        ldv5
    sub        cx,cx
    mov        bx,si
    jmp        ldv11

ldv7:    mov        di,0010h

ldv8:    shl        ax,1
    rcl        dx,1
    rcl        si,1
    cmp        si,cx
    jb        ldv10
    jnz        ldv9
    cmp        dx,bx
    jb        ldv10

ldv9:    sub        dx,bx
    sbb        si,cx
    inc        ax

ldv10:    dec        di
    jnz        ldv8
    mov        cx,si
    mov        bx,dx
    sub        dx,dx

ldv11:    test        Wptr[bp],8000h
    jz        ldv12
    not        dx
    neg        ax
    sbb        dx,-1

ldv12:    test        Wptr[bp+2],8000h
    jz        ldv13
    not        cx
    neg        bx
    sbb        cx,-1

ldv13:    add        sp,4
    pop        bp
    ret
lDiv    ENDP


    END