62 lines
2.0 KiB
NASM
62 lines
2.0 KiB
NASM
; ***************************************************************************
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; copyright : (C) 2023 by Martin Preuss
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; email : martin@libchipcard.de
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;
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; ***************************************************************************
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; * This file is part of the project "AqHome". *
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; * Please see toplevel file COPYING of that project for license details. *
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; ***************************************************************************
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; ***************************************************************************
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; macros
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; ---------------------------------------------------------------------------
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; Utils_WaitNanoSecs waittime_in_ns , cyles_already_used , waitcount_register
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;
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; Please note: times smaller than 5000 are unreliable on 1MHZ AtTiny84 (takes much longer
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; than requested, probably due to the fact that one cpu instrction already takes 1us to 2us).
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;
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; cycles already used will be subtracted from the delay
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; the waittime resolution is 1 cycle (delay from exact to +1 cycle)
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; the maximum delay at 20MHz (50ns/clock) is 38350ns
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; waitcount register must specify an immediate register
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; taken from https://www.mikrocontroller.net/articles/AVR_Assembler_Makros#Verz%C3%B6gerung_um_X_Nanosekunden
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;
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.set Osc_Hz = clock ; 1 MHz
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.set cycle_time_ns = (1000000000 / Osc_Hz) ; clock duration
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.macro Utils_WaitNanoSecs
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.set cycles = ((@0 + cycle_time_ns - 1) / cycle_time_ns - @1)
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.if (cycles > (255 * 3 + 2))
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.error "MACRO Utils_WaitNanoSecs - too many cycles to burn"
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.else
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.if (cycles > 6)
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.set loop_cycles = (cycles / 3)
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ldi @2,loop_cycles
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dec @2
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brne pc-1
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.set cycles = (cycles - (loop_cycles * 3))
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.endif
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.if (cycles > 0)
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.if (cycles & 4)
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rjmp pc+1
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rjmp pc+1
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.endif
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.if (cycles & 2)
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rjmp pc+1
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.endif
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.if (cycles & 1)
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nop
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.endif
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.endif
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.endif
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.endmacro
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