HPAVC/HPAVC CD-ROM.iso/pc/BIRTHSRC.ZIP/FIXED.INC

Text File | 1993-11-23 | 8.8 KB | 349 lines

;╔════════════════════════════════════════════════╗
;║  Name:Fixed_Point_Routines____________  V01.00 ║
;║                                                ║
;║  Modified:15-Nov-93                         FB ║
;╚════════════════════════════════════════════════╝
;

;**************************************************

INCLUDE TRIGTABL.DAT

;--------------------------------------------------
; FixedMul - Fixed Point Multiplication and rounding
;    IN     : - eax
;               edx
;   OUT     : - eax
;  Modified : eax,edx
;  Vars Used: -

FixedMul        PROC

    imul    edx
    add     eax,8000h
    adc     edx,0
    shrd    eax,edx,16
    ret


FixedMul        ENDP
;--------------------------------------------------
; FixedDiv - Fixed Point Division (No Rounding!)
;    IN     : - edx     (edx div ebx)
;               ebx
;   OUT     : - eax
;  Modified : eax,ebx,edx

FixedDiv        PROC

       ;mov     edx,A
    xor     eax,eax
    shrd    eax,edx,16
    sar     edx,16
    idiv    ebx
    ret

FixedDiv        ENDP
;--------------------------------------------------
; Sin - Fixed Point Sine (lookup - circle=1024 steps)
;    IN     : bx  (deg 0..1023)
;   OUT     : eax
;  Modified : bx dx
Sin            PROC

       ;mov     bx,DEG          ;0-> 1, 256-> 0, 512-> -1, 768-> 0
    add     bx,768          ;convert sin to cos
    xor     dx,dx
    and     bx,1023         ;Maxdegree
    shl     bx,1
    mov     ax,cs:trigtable[bx]
    cmp     bx,256*2          ;is it negative
    jbe     fcosi2
    cmp     bx,768*2
    jae     fcosi2
    dec     dx
fcosi2:
    shl     eax,16
    shrd    eax,edx,16
    ret

Sin            ENDP
;--------------------------------------------------
; Cos - Fixed Point Cosine (lookup - circle=1024 steps)
;    IN     : bx  (deg 0..1023)
;   OUT     : eax
;  Modified : bx dx
Cos            PROC

       ;mov     bx,DEG          ;0-> 1, 256-> 0, 512-> -1, 768-> 0
    xor     dx,dx
    and     bx,1023         ;Maxdegree
    shl     bx,1
    mov     ax,cs:trigtable[bx]
    cmp     bx,256*2          ;is it negative
    jbe     fcosi
    cmp     bx,768*2
    jae     fcosi
    dec     dx
fcosi:
    shl     eax,16
    shrd    eax,edx,16
    ret

Cos            ENDP
;--------------------------------------------------
; SqrtLP - Fixed Point Square Root (Low Precision)
;    IN     : ecx
;   OUT     : eax
;  Modified : ebx,ecx,edx

SqrtLP           PROC
;NOTE:
;this function only gives a 8.8 precision !!!!!!!!!!!!!

    xor     eax,eax

    mov     ebx,40000000h
sqrtLP1:
    mov     edx,ecx         ;edx = val
    sub     edx,ebx         ;val - bitsqr
    jl      sqrtLP2
    sub     edx,eax         ;val - root
    jl      sqrtLP2
    mov     ecx,edx         ;val >= (root+bitsqr) -> accept subs
    shr     eax,1           ;root >> 1
    or      eax,ebx         ;root | bitsqr
    shr     ebx,2           ;bitsqr>>2
    jnz     sqrtLP1
    shl     eax,8
    ret
sqrtLP2:
    shr     eax,1           ;val < (root+bitsqr) -> dont change val
    shr     ebx,2           ;bitsqr>>2
    jnz     sqrtLP1
    shl     eax,8
    ret

SqrtLP           ENDP
;--------------------------------------------------
; Sqrt - Fixed Point Square Root (High/Normal Precision)
;    IN     : ecx
;   OUT     : eax
;  Modified : ebx,ecx,edx
Sqrt         PROC

;This is the High Precision version for the sqrt.
;It gives the optimal 8.16 precision but takes
;a little longer (24 iterations, 48 bits intead of
;16 iterations and 32 bits)

    xor     eax,eax         ;eax is root
    mov     ebx,40000000h
sqrt1:
    mov     edx,ecx         ;edx = val
    sub     edx,ebx         ;val - bitsqr
    jb      sqrt2
    sub     edx,eax         ;val - root
    jb      sqrt2
    mov     ecx,edx         ;val >= (root+bitsqr) -> accept subs
    shr     eax,1           ;root >> 1
    or      eax,ebx         ;root | bitsqr
    shr     ebx,2           ;bitsqr>>2
    jnz     sqrt1
    jz      sqrt5
sqrt2:
    shr     eax,1           ;val < (root+bitsqr) -> dont change val
    shr     ebx,2           ;bitsqr>>2
    jnz     sqrt1
; we now have the 8.8 precision

sqrt5:
    mov     ebx,00004000h
    shl     eax,16
    shl     ecx,16
sqrt3:
    mov     edx,ecx         ;edx = val
    sub     edx,ebx         ;val - bitsqr
    jb      sqrt4
    sub     edx,eax         ;val - root
    jb      sqrt4
    mov     ecx,edx         ;val >= (root+bitsqr) -> accept subs
    shr     eax,1           ;root >> 1
    or      eax,ebx         ;root | bitsqr
    shr     ebx,2           ;bitsqr>>2
    jnz     sqrt3
    ret
sqrt4:
    shr     eax,1           ;val < (root+bitsqr) -> dont change val
    shr     ebx,2           ;bitsqr>>2
    jnz     sqrt3
    ret

Sqrt           ENDP
;--------------------------------------------------
; RotateX - Fixed Point X-Axis-rotation
;    IN     : gs:si     (ptr to x,y,z fixed point coords)
;             Xsin      ( sine )
;             Xcos      ( cosine )
;   OUT     :
;             ebx       (y)
;             ecx       (z)
;  Modified : eax,edx,ebp
RotateX         PROC

    mov     eax,gs:[si+4]       ;get y value
    imul    Xcos                ; y*cos
    add     eax,8000h
    adc     edx,0
    shrd    eax,edx,16
    mov     ebp,eax

    mov     eax,gs:[si+8]       ;get z value
    imul    Xsin                ; z*sin
    add     eax,8000h
    adc     edx,0
    shrd    eax,edx,16
    sub     ebp,eax             ; y*cos-z*sin

    mov     eax,gs:[si+4]       ;get y value
    imul    Xsin                ; y*sin
    add     eax,8000h
    adc     edx,0
    shrd    eax,edx,16
    mov     ebx,ebp             ;set up return register (y)
    mov     ebp,eax

    mov     eax,gs:[si+8]       ;get z value
    imul    Xcos                ; z*cos
    add     eax,8000h
    adc     edx,0
    shrd    eax,edx,16
    add     ebp,eax             ; y*sin+z*cos
    mov     ecx,ebp             ;set up return register (z)

    ret

RotateX         ENDP
;--------------------------------------------------
; RotateY - Fixed Point Y-Axis-rotation
;    IN     : gs:si     (ptr to x,y,z fixed point coords)
;             Ysin      ( sine )
;             Ycos      ( cosine )
;   OUT     :
;             ebx       (x)
;             ecx       (z)
;  Modified : eax,edx,ebp
RotateY         PROC

    mov     eax,gs:[si]         ;get x value
    imul    Ycos                ; x*cos
    add     eax,8000h
    adc     edx,0
    shrd    eax,edx,16
    mov     ebp,eax

    mov     eax,gs:[si+8]       ;get z value
    imul    Ysin                ; z*sin
    add     eax,8000h
    adc     edx,0
    shrd    eax,edx,16
    sub     ebp,eax             ; x*cos-z*sin

    mov     eax,gs:[si+8]       ;get z value
    imul    Ycos                ; z*cos
    add     eax,8000h
    adc     edx,0
    shrd    eax,edx,16
    mov     ebx,ebp             ;set up return register (x)
    mov     ebp,eax             ; z*cos

    mov     eax,gs:[si]         ;get x value
    imul    Ysin                ; x*sin
    add     eax,8000h
    adc     edx,0
    shrd    eax,edx,16
    add     ebp,eax             ; z*cos+x*sin
    mov     ecx,ebp             ;set up return register (z)

    ret

RotateY         ENDP
;--------------------------------------------------
; RotateZ - Fixed Point Z-Axis-rotation
;    IN     : gs:si     (ptr to x,y,z fixed point coords)
;             Zsin      ( sine )
;             Zcos      ( cosine )
;   OUT     :
;             ebx       (x)
;             ecx       (y)
;  Modified : eax,edx,ebp
RotateZ         PROC

    mov     eax,gs:[si]         ;get x value
    imul    Zcos                ; x*cos
    add     eax,8000h
    adc     edx,0
    shrd    eax,edx,16
    mov     ebp,eax

    mov     eax,gs:[si+4]       ;get y value
    imul    Zsin                ; y*sin
    add     eax,8000h
    adc     edx,0
    shrd    eax,edx,16
    sub     ebp,eax             ; x*cos-y*sin

    mov     eax,gs:[si]         ;get x value
    imul    Zsin                ; x*sin
    add     eax,8000h
    adc     edx,0
    shrd    eax,edx,16
    mov     ebx,ebp             ;set up return register (x)
    mov     ebp,eax

    mov     eax,gs:[si+4]       ;get y value
    imul    Zcos                ; y*cos
    add     eax,8000h
    adc     edx,0
    shrd    eax,edx,16
    add     ebp,eax             ; x*sin+y*cos
    mov     ecx,ebp             ;set up return register (y)

    ret

RotateZ         ENDP
;--------------------------------------------------
; Three2TwoD - Fixed Point (x,y,z) to (x,y)
;    IN     : gs:si     (ptr to x,y,z fixed point coords)
;             ebx       (z) value  (usually gs:[si+8])
;   OUT     :
;             ecx       (x)
;             edx       (y)
;  Modified : eax
Three2TwoD      PROC

    mov     edx,gs:[si+4]           ;get y-value
    shl     edx,7                   ;zoom factor = 128

    xor     eax,eax
    shrd    eax,edx,16
    sar     edx,16
    idiv    ebx
    mov     ecx,eax

    mov     edx,gs:[si]             ;get x-value
    shl     edx,7                   ;zoom factor = 128

    xor     eax,eax
    shrd    eax,edx,16
    sar     edx,16
    idiv    ebx
    mov     edx,ecx
    mov     ecx,eax

    ret

Three2TwoD      ENDP
;--------------------------------------------------
;**************************************************