6502
/
foco65
mirror of https://github.com/piotr-wiszowaty/foco65.git
1
0
Fork 0
Code Issues Projects Releases Wiki Activity

Add word: m*

This commit is contained in:
Piotr Wiszowaty 2014-07-24 21:59:46 +02:00 committed by Piotr Wiszowaty
parent 6c4dd5ee2c
commit 3129056a48
1 changed files with 102 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

102
foco65
View File

@ -1685,6 +1685,108 @@ plus_loop_end
ror pstack,x
jmp next
[end-code] ;
: m* ( n1 n2 -- d-prod )
[label] m_star
[code]
; z := n2
lda pstack,x
sta z
lda pstack+1,x
sta z+1
; w := n1
lda pstack+2,x
sta w
lda pstack+3,x
sta w+1
; save sign
eor z+1
sta cntr+1
; abs(n1)
lda w+1
bpl m_star_n1_plus
lda w
eor #$FF
clc
adc #1
sta w
lda w+1
eor #$FF
adc #0
sta w+1
m_star_n1_plus
; abs(n2)
lda z+1
bpl m_star_n2_plus
lda z
eor #$FF
clc
adc #1
sta z
lda z+1
eor #$FF
adc #0
sta z+1
m_star_n2_plus
; clear result
lda #0
sta tmp+0
sta tmp+1
sta tmp+2
sta tmp+3
; tmp := w * z
ldy #16
m_star_loop
lsr w+1
ror w
bcc m_star_next
lda z
clc
adc tmp+2
sta tmp+2
lda z+1
adc tmp+3
sta tmp+3
m_star_next
clc
ror tmp+3
ror tmp+2
ror tmp+1
ror tmp+0
dey
bne m_star_loop
; apply sign
lda cntr+1
bpl m_star_done
lda tmp+0
eor #$FF
clc
adc #1
sta tmp+0
lda tmp+1
eor #$FF
adc #0
sta tmp+1
lda tmp+2
eor #$FF
adc #0
sta tmp+2
lda tmp+3
eor #$FF
adc #0
sta tmp+3
m_star_done
; push result on the stack
lda tmp+0
sta pstack+2,x
lda tmp+1
sta pstack+3,x
lda tmp+2
sta pstack+0,x
lda tmp+3
sta pstack+1,x
jmp next
[end-code] ;
"""
parser = argparse.ArgumentParser()