;; #LAYOUT# STD *       #TAKE
;; #LAYOUT# X16 BASIC_0 #TAKE-OFFSET 2000
;; #LAYOUT# *   BASIC_0 #TAKE
;; #LAYOUT# *   *       #IGNORE

; This file is under the MIT license, it contains code released by Microsoft Corporation.
; See LICENSE for more information.

; Math package - toggle FAC1 sign (if not 0)
;
; This is verified to be identical to the original Microsoft implementation where it was named NEGOP.
;
; See also:
; - [CM64] Computes Mapping the Commodore 64 - page 117
; - https://www.c64-wiki.com/wiki/Floating_point_arithmetic
;

toggle_sign_FAC1:
        lda FAC1_exponent
        beq NEGRTS
        lda FAC1_sign
        eor #$FF
        sta FAC1_sign
NEGRTS:
        rts
