27 lines
556 B
ArmAsm
27 lines
556 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 - evaluate FAC1 sign, to .A
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//
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// Output:
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// - .A - 0 for FAC1 equal 0, 1 for FAC1 > 0, -1 for FAC1 < 0
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//
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// See also:
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// - [CM64] Computes Mapping the Commodore 64 - page 115
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// - https://www.c64-wiki.com/wiki/Floating_point_arithmetic
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// - https://codebase64.org/doku.php?id=base:kernal_floating_point_mathematics
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//
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sgn_FAC1_A:
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lda FAC1_exponent
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beq !+
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lda FAC1_sign
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bne !+
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lda #$01
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!:
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rts
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