Rikard Nordgren
5a3f65efa4
Also change to only use bit 7 as sign in FAC1 and FAC2 (as the original BASIC does) to simplify implementations.
31 lines
617 B
ArmAsm
31 lines
617 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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; Math package - fetch FAC1 from RAM location
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;
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; Input:
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; - .A - address low byte
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; - .Y - address high byte
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;
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; Output:
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; - .A - FAC1 exponent, affects status flags
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; - .Y - always 0
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;
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; Preserves:
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; - .X - (experimentation with original ROM)
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;
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; See also:
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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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mov_MEM_FAC1:
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sty INDEX+1
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sta INDEX+0
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; FALLTHROUGH to get_FAC1_via_INDEX
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