28 lines
569 B
ArmAsm
28 lines
569 B
ArmAsm
// #LAYOUT# STD * #TAKE
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// #LAYOUT# X16 BASIC_0 #TAKE-OFFSET 2000
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// #LAYOUT# * BASIC_0 #TAKE
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// #LAYOUT# * * #IGNORE
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//
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// Math package - toggle FAC1 sign (if not 0)
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//
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// See also:
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// - [CM64] Computes Mapping the Commodore 64 - page 117
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// - https://www.c64-wiki.com/wiki/Floating_point_arithmetic
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//
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toggle_sign_FAC1:
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lda FAC1_exponent
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beq !+ // do not toggle the sign if value is 0
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// FALLTROUGH
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toggle_sign_FAC1_skipcheck: // entry for other routines
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lda FAC1_sign
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eor #$FF
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sta FAC1_sign
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!:
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rts
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