23 lines
514 B
ArmAsm
23 lines
514 B
ArmAsm
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iec_wait20us:
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;; Wait 20usec
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;; PAL:
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;; - CPU frequency 0.985248 MHz, we need to waste at least 20 cycles
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;; NTSC:
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;; - CPU frequency 1.022727 MHZ, we need to waste at least 21 cycles
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;; Waste cycles by reading some unimportant memory location
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;; in order not to clutter VICE debug logs
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ora $03FF ; 4 cycles
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ora $03FF ; 4 cycles
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rts ; 6 cycles
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;; 6 cycles JSR to routine,
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;; 14 cycles routine with RTS
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;; 1 cycle to fetch next instruction
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;; ---
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;; 21 cycles
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