30 lines
574 B
ArmAsm
30 lines
574 B
ArmAsm
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//
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// JiffyDOS transfer preparation routine
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//
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#if CONFIG_IEC_JIFFYDOS
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jiffydos_prepare:
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// We need to preserve 3 lowest bits of CIA2_PRA, they contain important
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// data - fortunately, the bits are never changed by external devices
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// Use C3PO for this, as afterwards we have to set there 0 nevertheless
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lda CIA2_PRA
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and #%00000111
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sta C3PO
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// Hide sprites; JiffyDOS timing regime is very strict, before transmitting
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// anything we need to make sure nothing will steal the cycles
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lda VIC_SPENA
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ldx #$00
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stx VIC_SPENA
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rts
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#endif // CONFIG_IEC_JIFFYDOS
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