50 lines
811 B
ArmAsm
50 lines
811 B
ArmAsm
;=======================
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; HGR Partial Restore
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;=======================
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; loads from $40 (page2)
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; save to $20 (page1)
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; restores from X = A<=to<=X
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; Y = SAVED_Y1 to SAVED_Y2
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hgr_partial_restore:
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sta partial_restore_x1_smc+1
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stx partial_restore_x2_smc+1
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ldx SAVED_Y2 ; handle wrap around
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cpx #192
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bcc partial_restore_yloop ; assume > 192 off screen negative
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ldx #0 ; X is end y-co-ord?
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partial_restore_yloop:
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lda hposn_low,X
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sta prx_smc2+1
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sta prx_smc1+1
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lda hposn_high,X
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sta prx_smc2+2
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clc
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adc #$20
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sta prx_smc1+2
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partial_restore_x2_smc:
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ldy #$27
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partial_restore_xloop:
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prx_smc1:
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lda $d000,Y
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prx_smc2:
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sta $d000,Y
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dey
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partial_restore_x1_smc:
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cpy #$00
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bpl partial_restore_xloop
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dex
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cpx SAVED_Y1
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bpl partial_restore_yloop ; urgh bcs gets stuck
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rts
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