26 lines
599 B
ArmAsm
26 lines
599 B
ArmAsm
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iec_wait100us:
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;; Wait 100usec
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;; PAL:
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;; - CPU frequency 0.985248 MHz, we need to waste at least 99 cycles
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;; NTSC:
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;; - CPU frequency 1.022727 MHZ, we need to waste at least 103 cycles
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;; Waste cycles by reading some unimportant memory location
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;; (in a loop) in order not to clutter VICE debug logs
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;; Waste cycles in a loop
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ldy #$12 ; 2 cycles
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* dey ; 2 cycles * 18
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bpl - ; 3 cycles * 17 + 2 cycles
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rts ; 6 cycles
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;; 6 cycles JSR to routine,
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;; 97 cycles routine with RTS
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;; 1 cycle to fetch next instruction
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;; ---
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;; 104 cycles
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