38 lines
630 B
ArmAsm
38 lines
630 B
ArmAsm
#if ROM_LAYOUT_STD || (ROM_LAYOUT_M65 && SEGMENT_KERNAL_0)
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//
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// Note: damages .X
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//
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#if CONFIG_IEC
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iec_wait60us:
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// Wait 60usec
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// PAL:
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// - CPU frequency 0.985248 MHz, we need to waste at least 60 cycles
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// NTSC:
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// - CPU frequency 1.022727 MHz, we need to waste at least 62 cycles
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// Waste cycles in a loop
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ldx #$0A // 2 cycles
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!: dex // 2 cycles * 10
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bpl !- // 3 cycles * 9 + 2 cycles
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rts // 6 cycles
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// 6 cycles JSR to routine,
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// 57 cycles routine with RTS
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// 1 cycle to fetch next instruction
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// ---
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// 64 cycles
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#endif // CONFIG_IEC
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#endif // ROM layout
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