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Small Videx optimization.

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Bobbi Webber-Manners 2024-08-05 17:29:47 -04:00
parent 53b40ceca7
commit 88f15c08ae
1 changed files with 17 additions and 12 deletions
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29
drivers/a2vt100.s
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@ -1053,6 +1053,7 @@ CO2 pla ; restore registers
rts
.else
COff
; TODO - write me
rts
.endif
@ -1094,6 +1095,7 @@ COn4 pla
rts
.else
COn
; TODO - write me
rts
.endif
@ -1243,8 +1245,8 @@ VidexSetVec
lda videxstart+1
sta xVector+1
cpy #$00
beq VP2 ; Row zero -> skip over loop
VP1 lda xVector ; row * 80 -> xVector (double prec)
beq VSV2 ; Row zero -> skip over loop
VSV1 lda xVector ; row * 80 -> xVector (double prec)
clc
adc #80
sta xVector
@ -1252,8 +1254,8 @@ VP1 lda xVector ; row * 80 -> xVector (double prec)
adc #00
sta xVector+1
dey
bne VP1
VP2 lda xVector ; Add col -> xVector
bne VSV1
VSV2 lda xVector ; Add col -> xVector
clc
adc VSVTmp
sta xVector
@ -1267,16 +1269,14 @@ VP2 lda xVector ; Add col -> xVector
asl ; Multiply by 4
asl ; ..
tax ; Will return page*4 in X
beq VP4 ; Page zero -> skip over loop
VP3 lda xVector+1 ; MSB
beq VSV4 ; Page zero -> skip over loop
VSV3 lda xVector+1 ; MSB
sec
sbc #$02 ; Subtract 2 from MSB -> sub 512 from value
sta xVector+1
dey
bne VP3
VP4 lda xVector+1
clc ; Add $CC to MSbyte to make address
adc #$cc
bne VSV3
VSV4 lda xVector+1
sta BASH
rts
@ -1298,8 +1298,13 @@ VidexPage
; Affects: Y
; -------------------------------------
VidexPrint
ldy #$00
sta (BASL),y
ldy BASH
bne VP1
ldy BASL
sta $cc00,y
rts
VP1 ldy BASL
sta $cd00,y
rts
.endif