41 lines
1.0 KiB
ArmAsm
41 lines
1.0 KiB
ArmAsm
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//
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// Tape (turbo) helper routine - storing byte uder I/O
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//
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// This helper routine is meant to be copiet to the start of CPU stack.
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// Original ROM tape loading routines uses this area to store information
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// about bytes that did not read properly for the first time
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// (see Mapping the C64, page 47); this mechanism is useless for turbo tape,
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// but it means we can safely use this area for our purposes
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#if CONFIG_TAPE_TURBO
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.label __tape_turbo_bytestore = STACK
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.label __tape_turbo_bytestore_defmap = __tape_turbo_bytestore + 7
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.label __tape_turbo_bytestore_size = __tape_turbo_bytestore_source_end - tape_turbo_bytestore_source
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tape_turbo_bytestore_source:
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// Set all memory as RAM, tape motor ON
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ldx #$00
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stx CPU_R6510
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// Store byte in memory
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sta (MEMUSS), y
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// Restore default memory layout
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ldx #$00 // value will be determined later, offset from start: 7 bytes
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stx CPU_R6510
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// Go back
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rts
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__tape_turbo_bytestore_source_end:
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#endif // CONFIG_TAPE_TURBO
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