tawny factor.asm

factor.asm

****
** factor.asm -- factor 32 bit numbers
****
    AORG >0000
    DATA WPA    ; WP
    DATA START  ; PC

    AORG >1000  ; workspaces
WPA BSS >20
WPB BSS >20

    AORG >1800
START
    LI 0, >1700        ; output pointer
    MOV @>17FC, 3      ; N high
    MOV @>17FE, 4      ; N low

    CI 3, >0000
    JNE FACTOR_INIT
    CI 4, >0000
    JNE FACTOR_INIT
    LI 1, >0000
    MOV 1, *0+
    MOV 1, *0+
    IDLE

FACTOR_INIT
    LI 5, >0002        ; divisor

FACTOR_LOOP
    CI 3, >0000
    JNE CHECK_DIV
    CI 4, >0001
    JEQ DONE

CHECK_DIV
    MOV 5, 9
    MPY 5, 9
    C 3, 9
    JEQ CMP_LOW
    JH REMAINING_32
    JMP TRY_DIV

CMP_LOW
    C 4, R10
    JH REMAINING_32
    JMP TRY_DIV

TRY_DIV
    MOV 3, R11
    MOV 4, R12
    LI 6, >0000        ; remainder
    LI 7, >0000        ; quotient high
    LI 8, >0000        ; quotient low
    LI 2, >0020        ; 32 bits

DIV32_LOOP
    LI 9, >0000
    SLA 4, 1
    JOC DIV32_LOW_CARRY
    JMP DIV32_LOW_DONE
DIV32_LOW_CARRY
    LI 9, >0001
DIV32_LOW_DONE
    LI R10, >0000
    SLA 3, 1
    JOC DIV32_HIGH_CARRY
    JMP DIV32_HIGH_DONE
DIV32_HIGH_CARRY
    LI R10, >0001
DIV32_HIGH_DONE
    CI 9, >0000
    JEQ DIV32_SKIP_HIGH_LSB
    ORI 3, >0001
DIV32_SKIP_HIGH_LSB
    SLA 6, 1
    CI R10, >0000
    JEQ DIV32_SKIP_REM_LSB
    ORI 6, >0001
DIV32_SKIP_REM_LSB
    LI 9, >0000
    SLA 8, 1
    JOC DIV32_QLOW_CARRY
    JMP DIV32_QLOW_DONE
DIV32_QLOW_CARRY
    LI 9, >0001
DIV32_QLOW_DONE
    SLA 7, 1
    CI 9, >0000
    JEQ DIV32_QSKIP_HIGH_LSB
    ORI 7, >0001
DIV32_QSKIP_HIGH_LSB
    C 5, 6
    JHE DIV32_REM_GE
    JMP DIV32_REM_LT
DIV32_REM_GE
    S 5, 6
    ORI 8, >0001
DIV32_REM_LT
    DEC 2
    JNE DIV32_LOOP

    CI 6, >0000
    JEQ FOUND_FACTOR

    MOV R11, 3
    MOV R12, 4
    CI 5, >0002
    JEQ SET_DIV3
    AI 5, >0002
    JMP FACTOR_LOOP

SET_DIV3
    LI 5, >0003
    JMP FACTOR_LOOP

FOUND_FACTOR
    MOV 7, 3
    MOV 8, 4
    LI 1, >0000
    MOV 1, *0+
    MOV 5, *0+
    JMP FACTOR_LOOP

REMAINING_32
    MOV 3, *0+
    MOV 4, *0+
    JMP DONE

DONE
    LI 1, >0000
    MOV 1, *0+
    MOV 1, *0+
    IDLE