// #LAYOUT# STD *       #TAKE
// #LAYOUT# *   BASIC_0 #TAKE
// #LAYOUT# *   *       #IGNORE

//
// Math package - move FAC1 to FAC2
//
// Output (all found by experimentation):
// - .A - FAC1 exponent
// - .X - always 0
//
// Preserves (found by experimentation):
// - .Y
//
// Note:
// - observed that original ROM always clears FACOV, not sure why
//
// See also:
// - [CM64] Computes Mapping the Commodore 64 - page 115
// - https://www.c64-wiki.com/wiki/BASIC-ROM
// - https://www.c64-wiki.com/wiki/Floating_point_arithmetic
//

MOVFA:

	// Copy the exponent
	lda FAC1_exponent
	sta FAC2_exponent
	beq !+                             // for 0 no need to copy mantissa and sign

	// Copy the mantissa
	lda FAC1_mantissa+0
	sta FAC2_mantissa+0
	lda FAC1_mantissa+1
	sta FAC2_mantissa+1
	lda FAC1_mantissa+2
	sta FAC2_mantissa+2
	lda FAC1_mantissa+3
	sta FAC2_mantissa+3

	// Copy the sign
	lda FAC1_sign
	sta FAC2_sign

	lda FAC1_exponent
!:
	// Duplicate the original ROM behaviour
	ldx #$00
	stx FACOV

	rts