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Use new multiplication routine.

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git-svn-id: svn://svn.cc65.org/cc65/trunk@4439 b7a2c559-68d2-44c3-8de9-860c34a00d81
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uz 2009-11-04 13:46:16 +00:00
parent 7c804513fa
commit 56e035635b
1 changed files with 23 additions and 14 deletions
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37
libsrc/tgi/tgi_vectorchar.s
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@ -9,7 +9,7 @@
.export _tgi_vectorchar
.import push0ax, tosmuleax
.import imul16x16r32, umul16x16r32, negax, negeax
.include "tgi-kernel.inc"
.include "zeropage.inc"
@ -127,9 +127,10 @@ Loop: lda _tgi_textscalew+0
.proc GetProcessedCoord
; Push the scale factor
; Save scale factor as left operand for multiplication
jsr push0ax
sta ptr1
stx ptr1+1
; Load delta value
@ -144,23 +145,28 @@ Loop: lda _tgi_textscalew+0
: asl a ; Flag into carry
ror Flag
; Sign extend the value
; Since we know that the scale factor is always positive, we will remember
; the sign of the coordinate offset, make it positive, do an unsigned mul
; and negate the result if the vector was negative. This is faster than
; relying on the signed multiplication, which will do the same, but for
; both operands.
ldx #0
sta tmp1 ; Remember sign of vector offset
cmp #$80 ; Sign bit into carry
bcc :+
dex
: ror a ; Sign extend the value
ror a ; Sign extend the value
bpl :+
eor #$FF
clc
adc #$01 ; Negate
: ldx #$00 ; High byte is always zero
; Multiplicate with the scale factor.
stx sreg
stx sreg+1
jsr tosmuleax ; Multiplicate
jsr umul16x16r32 ; Multiplicate
; The result is a 16.8 fixed point value. Round and return it.
; The result is a 16.8 fixed point value. Round it.
cmp #$80 ; Check digits after the dec point
cmp #$80 ; frac(val) >= 0.5?
txa
adc #$00
tay
@ -168,7 +174,10 @@ Loop: lda _tgi_textscalew+0
adc #$00
tax
tya
rts
bit tmp1 ; Check sign
bpl :+
jmp negax ; Negate result if necessary
: rts
.endproc