QBasic & Borland Pascal & C/Delphi5.iso/Runimage/Delphi50/Source/Rtl/Sys/POW10.ASM

Assembly Source File | 1999-08-11 | 4.2 KB | 230 lines

; *******************************************************
; *                            *
; *     Delphi Runtime Library                          *
; *                            *
; *    Copyright (c) 1996,98 Inprise Corporation    *
; *                            *
; *******************************************************

    INCLUDE    SE.ASM

    .386
    .MODEL    FLAT

    PUBLIC    _Pow10,FPower10

    .CODE

;    FUNCTION _Pow10( val: Extended; int pow: Integer ) : Extended;

_Pow10    PROC

; ->    FST(0)    val
; ->    EAX    Power
; <-    FST(0)    val * 10**Power

;    This routine generates 10**power with no more than two
;    floating point multiplications. Up to 10**31, no multiplications
;    are needed.

FPower10:

    TEST    EAX,EAX
    JL    @@neg
    JE    @@exit
    CMP    EAX,5120
    JGE    @@inf
    MOV    EDX,EAX
    AND    EDX,01FH
    LEA    EDX,[EDX+EDX*4]
    FLD    tab0[EDX*2]
    FMULP

    SHR    EAX,5
    JE    @@exit

    MOV    EDX,EAX
    AND    EDX,0FH
    JE    @@skip2ndMul
    LEA    EDX,[EDX+EDX*4]
    FLD    tab1-10[EDX*2]
    FMULP

@@skip2ndMul:

    SHR    EAX,4
    JE    @@exit
    LEA    EAX,[EAX+EAX*4]
    FLD    tab2-10[EAX*2]
    FMULP

@@exit:
    RET

@@neg:
    NEG    EAX
    CMP    EAX,5120
    JGE    @@zero
    MOV    EDX,EAX
    AND    EDX,01FH
    LEA    EDX,[EDX+EDX*4]
    FLD    tab0[EDX*2]
    FDIVP

    SHR    EAX,5
    JE    @@exit

    MOV    EDX,EAX
    AND    EDX,0FH
    JE    @@skip2ndDiv
    LEA    EDX,[EDX+EDX*4]
    FLD    tab1-10[EDX*2]
    FDIVP

@@skip2ndDiv:

    SHR    EAX,4
    JE    @@exit
    LEA    EAX,[EAX+EAX*4]
    FLD    tab2-10[EAX*2]
    FDIVP

    RET

@@inf:
    FLD    inf
    RET

@@zero:
    FLDZ
    RET

inf    DT    7FFF8000000000000000R

if 0    ; unfortunately, tasm32 makes some numbers one bit too small...
tab0    DT    1E0
    DT    1E1
    DT    1E2
    DT    1E3
    DT    1E4
    DT    1E5
    DT    1E6
    DT    1E7
    DT    1E8
    DT    1E9
    DT    1E10
    DT    1E11
    DT    1E12
    DT    1E13
    DT    1E14
    DT    1E15
    DT    1E16
    DT    1E17
    DT    1E18
    DT    1E19
    DT    1E20
    DT    1E21
    DT    1E22
    DT    1E23
    DT    1E24
    DT    1E25
    DT    1E26
    DT    1E27
    DT    1E28
    DT    1E29
    DT    1E30
    DT    1E31

tab1    DT    1E32
    DT    1E64
    DT    1E96
    DT    1E128
    DT    1E160
    DT    1E192
    DT    1E224
    DT    1E256
    DT    1E288
    DT    1E320
    DT    1E352
    DT    1E384
    DT    1E416
    DT    1E448
    DT    1E480

tab2    DT    1E512
    DT    1E1024
    DT    1E1536
    DT    1E2048
    DT    1E2560
    DT    1E3072
    DT    1E3584
    DT    1E4096
    DT    1E4608

else    ;    these are better numbers ...

tab0    DT    3FFF8000000000000000R    ; 10**0
    DT    4002A000000000000000R    ; 10**1
    DT    4005C800000000000000R    ; 10**2
    DT    4008FA00000000000000R    ; 10**3
    DT    400C9C40000000000000R    ; 10**4
    DT    400FC350000000000000R    ; 10**5
    DT    4012F424000000000000R    ; 10**6
    DT    40169896800000000000R    ; 10**7
    DT    4019BEBC200000000000R    ; 10**8
    DT    401CEE6B280000000000R    ; 10**9
    DT    40209502F90000000000R    ; 10**10
    DT    4023BA43B74000000000R    ; 10**11
    DT    4026E8D4A51000000000R    ; 10**12
    DT    402A9184E72A00000000R    ; 10**13
    DT    402DB5E620F480000000R    ; 10**14
    DT    4030E35FA931A0000000R    ; 10**15
    DT    40348E1BC9BF04000000R    ; 10**16
    DT    4037B1A2BC2EC5000000R    ; 10**17
    DT    403ADE0B6B3A76400000R    ; 10**18
    DT    403E8AC7230489E80000R    ; 10**19
    DT    4041AD78EBC5AC620000R    ; 10**20
    DT    4044D8D726B7177A8000R    ; 10**21
    DT    4048878678326EAC9000R    ; 10**22
    DT    404BA968163F0A57B400R    ; 10**23
    DT    404ED3C21BCECCEDA100R    ; 10**24
    DT    405284595161401484A0R    ; 10**25
    DT    4055A56FA5B99019A5C8R    ; 10**26
    DT    4058CECB8F27F4200F3AR    ; 10**27
    DT    405C813F3978F8940984R    ; 10**28
    DT    405FA18F07D736B90BE5R    ; 10**29
    DT    4062C9F2C9CD04674EDFR    ; 10**30
    DT    4065FC6F7C4045812296R    ; 10**31

tab1    DT    40699DC5ADA82B70B59ER    ; 10**32
    DT    40D3C2781F49FFCFA6D5R    ; 10**64
    DT    413DEFB3AB16C59B14A3R    ; 10**96
    DT    41A893BA47C980E98CE0R    ; 10**128
    DT    4212B616A12B7FE617AAR    ; 10**160
    DT    427CE070F78D3927556BR    ; 10**192
    DT    42E78A5296FFE33CC930R    ; 10**224
    DT    4351AA7EEBFB9DF9DE8ER    ; 10**256
    DT    43BBD226FC195C6A2F8CR    ; 10**288
    DT    442681842F29F2CCE376R    ; 10**320
    DT    44909FA42700DB900AD2R    ; 10**352
    DT    44FAC4C5E310AEF8AA17R    ; 10**384
    DT    4564F28A9C07E9B09C59R    ; 10**416
    DT    45CF957A4AE1EBF7F3D4R    ; 10**448
    DT    4639B83ED8DC0795A262R    ; 10**480

tab2    DT    46A3E319A0AEA60E91C7R    ; 10**512
    DT    4D48C976758681750C17R    ; 10**1024
    DT    53EDB2B8353B3993A7E4R    ; 10**1536
    DT    5A929E8B3B5DC53D5DE5R    ; 10**2048
    DT    61378CA554C020A1F0A6R    ; 10**2560
    DT    67DBF9895D25D88B5A8BR    ; 10**3072
    DT    6E80DD5DC8A2BF27F3F8R    ; 10**3584
    DT    7525C46052028A20979BR    ; 10**4096
    DT    7BCAAE3511626ED559F0R    ; 10**4608
endif

_Pow10    ENDP

    END