67 lines
1017 B
ArmAsm
67 lines
1017 B
ArmAsm
// #LAYOUT# STD * #TAKE
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// #LAYOUT# M65 KERNAL_1 #TAKE
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// #LAYOUT# * * #IGNORE
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//
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// Tape head alignemnt tool - interrupt routine
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//
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#if CONFIG_TAPE_HEAD_ALIGN
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tape_head_align_irq:
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// Acknowledge interrupt
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asl VIC_IRQ
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// Clear table of pulses stored
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lda #$FF
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ldy #$3F
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!:
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sta __ha_pulses, y
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dey
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bpl !-
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// Ignore 2 first pulses, they can be garbage
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jsr tape_head_align_get_pulse
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jsr tape_head_align_get_pulse
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// Now, we can retrieve a pulse for the charts
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ldx #$00
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!:
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jsr tape_head_align_get_pulse
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// If we approached badlines again - we cannot use this measurement anymore
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lda VIC_SCROLY
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bmi !+ // branch if lower border
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lda VIC_RASTER
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cmp #$33 // first line where badline can occur
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bcs tape_head_align_irq_end
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!:
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// Store measurement
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tya
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sta __ha_pulses, x
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// Next iteration
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inx
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cpx #$40
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bne !--
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// FALLTROUGH
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tape_head_align_irq_end:
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jmp return_from_interrupt
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#endif // CONFIG_TAPE_HEAD_ALIGN
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