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171 lines
3.5 KiB
Plaintext
171 lines
3.5 KiB
Plaintext
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; File: FontMath.a
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;
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; Contains: xxx put contents here xxx
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;
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; Written by: xxx put writers here xxx
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;
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; Copyright: <09> 1990 by Apple Computer, Inc., all rights reserved.
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;
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; Change History (most recent first):
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;
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; <2> 11/5/90 MR Rename FixMulDiv to LongMulDiv [rb]
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; <1> 10/20/90 MR 68000 versions of some routines in FontMath.c. [rj]
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;
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; To Do:
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;
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Case On
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Blanks Off
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IF 0 THEN
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; long LongMulDiv(long a, long b, long c)
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LongMulDiv Func Export
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move.l (sp)+,a0
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lea (sp),a1 ; get parameters
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move.l (a1)+,d0 ; get a
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move.l (a1)+,d1 ; get b
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move.l (a1),d2 ; get c
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beq.s @div0
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bpl.s @1
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neg.l d2
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@1:
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asr.l #1,d2
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muls.l d1,d1:d0 ; compute a*b
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bpl.s @2
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neg.l d2
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@2:
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add.l d2,d0
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bfexts d2{0:1},d2
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addx.l d2,d1
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divs.l (a1),d1:d0 ; compute (a*b+c/2)/c
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bvc.s @3
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move.l (a1),d0
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@div0:
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eor.l d1,d0
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bmi.s @div1
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move.l #$7fffffff,d0
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bra.s @3
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@div1:
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move.l #$80000000,d0
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@3:
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jmp (a0)
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ENDIF
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; long ShortMulDiv(long a, short b, short c)
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;
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; d3 a
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; d4 b
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; d5 c
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; d6 sign
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;
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ShortMulDiv Func Export
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move.l (sp)+,a0 ; get return address
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move.l sp,a1 ; get parameters
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movem.l d3-d6,-(sp)
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@0:
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move.l (a1)+,d3 ; get a
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smi d6 ; set sign
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bpl.s @1
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neg.l d3 ; a = -a
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@1:
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move.l (a1)+,d4 ; get b
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bpl.s @2
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not.b d6 ; change sign
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neg.l d4 ; b = -b
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@2:
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move.l (a1)+,d5 ; get c
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bpl.s @3
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not.b d6 ; change sign
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neg.l d5 ; c = -c
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@3:
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move.w d3,d0 ; get a.lo
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mulu.w d4,d0 ; compute a.lo * b
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move.l d5,d1 ; get c
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asr.l #1,d1 ; compute c / 2
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add.l d1,d0 ; compute a.lo * b + c / 2
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move.l d0,d1
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clr.w d0
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swap d0 ; get (a.lo * b + c / 2).hi
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move.l d3,d2
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swap d2 ; get a.hi
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mulu.w d4,d2 ; compute a.hi * b
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add.l d2,d0 ; compute a.hi * b + (a.lo * b + c / 2).hi
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divu.w d5,d0 ; compute the hi word of the result
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bvs.s @div0
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bmi.s @div0
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swap d0 ; get the remainder of the division
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swap d1
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move.w d0,d1
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swap d1 ; put the remainder in hi word
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divu.w d5,d1 ; compute lo word of result
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move.w d1,d0 ;join result
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tst.b d6 ; check sign
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beq.s @done
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neg.l d0
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bra.s @done
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@div0:
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moveq #1,d0
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ror.l #1,d0 ; negative infinity
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tst.b d6 ; check sign
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bne.s @done
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not.l d0 ; positive infinity
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@done:
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movem.l (sp)+,d3-d6
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jmp (a0)
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; long ShortFracMul(long a, ShortFrac b)
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;
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; d0 hilong
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; d1 midlong
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; d2 lowlong
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; d3 a
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; d4 b
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; d5 sign
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;
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ShortFracMul Func Export
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move.l (sp)+,a0 ; get return address
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move.l sp,a1 ; get parameters
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movem.l d3-d5,-(sp)
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@0:
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move.l (a1)+,d3 ; get a
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smi d5 ; set sign
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bpl.s @1
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neg.l d3 ; a = -a
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@1:
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move.l (a1)+,d4 ; get b
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bpl.s @2
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not.b d5 ; change sign
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neg.l d4 ; b = -b
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@2:
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move.l d3,d1 ; get a
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swap d1 ; a.hi in d1.w
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mulu.w d4,d1 ; compute a.hi * b
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swap d1 ; (a.hi * b).lo in d1.hi and vice-versa
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move.w d1,d0 ; grab (a.hi * b).hi in d0.w
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move.w #$2000,d1 ; d1 + (1 << 13) { like clr.w and add.l }
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move.w d3,d2 ; get a.lo
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mulu.w d4,d2 ; compute a.lo * b
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add.l d1,d2 ; a.lo * b + ((a.hi * b).lo).hi + (1 << 13)
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cmp.l d2,d1 ; check for overflow
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bls.s @3
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addq #1,d0 ; carry bit
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@3:
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swap d0
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clr.w d0
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lsl.l #2,d0 ; d0 <<= 18
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andi.w #$c000,d2 ; kill low 14 bits
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rol.l #2,d2
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swap d2 ; d2 >>= 14
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add.l d2,d0 ; here's the unsigned answer
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tst.b d5 ; check sign
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beq.s @done
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neg.l d0
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@done:
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movem.l (sp)+,d3-d5
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jmp (a0)
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END
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