implemented 2 more simple math routines

STATUS.md

@@ -193,9 +193,10 @@ Floating point mathematical routines - not official, but well known and broadly
 | `$BB0F`   | `FDIV`       | PARTIAL  | needs `FDIVT`                                      |
 | `$BB12`   | `FDIVT`      | NOT DONE | divide FAC2 by FAC1, ignores sign                  |
 | `$BBA2`   | `MOVFM`      | PARTIAL  | not fully tested yet                               |
-| `$BBD4`   | `MOVMF`      | NOT DONE | copy FAC1 to memory location, rounds if asked      |
+| `$BBD4`   | `MOVFM2`     | NOT DONE | copy FAC1 to memory location, rounds if asked      |
 | `$BBFC`   | `MOVEF`      | NOT DONE | copy FAC2 to FAC1                                  |
-| `$BC0F`   | `MOVFA`      | NOT DONE | copy FAC1 to FAC2, skips rounding                  |
+| `$BC0C`   | `MOVAF`      | PARTIAL  | not fully tested                                   |
+| `$BC0F`   | `MOVFA`      | DONE     |                                                    |
 | `$BC1B`   | `ROUND`      | PARTIAL  | not tested                                         |
 | `$BC2B`   | `SIGN`       | NOT DONE | evaluate FAC1 sign                                 |
 | `$BC39`   | `SGN`        | NOT DONE | evaluate FAC1 sign, to FAC1                        |

c64/basic/,stubs_math/bbd4.MOVMF2.s

@@ -14,12 +14,11 @@
 // - .A - FAC1 exponent
 //
 // See also:
-// - [CM64] Computes Mapping the Commodore 64 - page 114
 // - https://www.c64-wiki.com/wiki/Floating_point_arithmetic
 // - https://codebase64.org/doku.php?id=base:kernal_floating_point_mathematics
 //
 
 // XXX provide implementation
 
-MOVFM:
+MOVFM2:
 	STUB_IMPLEMENTATION()

c64/basic/math/MOVFA.s

@@ -0,0 +1,51 @@
+// #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

c64/basic/math/MOVFM.s

@@ -21,7 +21,7 @@
 
 // XXX test this
 
-MOVMF:
+MOVFM:
 
 	// Checked in the available documentation:
 	// - https://www.c64-wiki.com/wiki/Floating_point_arithmetic

c64/basic/math/ROUND.s

@@ -43,7 +43,7 @@ ROUND:
 	inc FAC1_exponent
 	bne round_zero_FACOV
 
-	// If w are here, it means the exponent wrapped around to $00; put it back to $FF
+	// If we are here, it means the exponent wrapped around to $00; put it back to $FF
 
 	dec FAC1_exponent
 

c64/basic/math/bba2.MOVFM.jmp.s

@@ -4,4 +4,4 @@
 
 // Just a compatibility jump - our routine is longer than original one
 
-	jmp MOVMF
+	jmp MOVFM

c64/basic/math/bc0c.MOVAF.s

@@ -3,15 +3,20 @@
 // #LAYOUT# *   *       #IGNORE
 
 //
-// Math package - copy FAC1 to FAC2, skips rounding
+// Math package - round and move FAC1 to FAC2
+//
+// Output:
+// - .A - FAC1 exponent
 //
 // 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
-// - https://codebase64.org/doku.php?id=base:kernal_floating_point_mathematics
 //
 
-// XXX provide implementation
+MOVAF:
 
-MOVFA:
+	// First round FAC1
-	STUB_IMPLEMENTATION()
+	jsr ROUND
+
+	// FALLTROUGH to MOVFA

c64/basic/math/bc0f.MOVFA.jmp.s

@@ -0,0 +1,7 @@
+// #LAYOUT# STD *       #TAKE
+// #LAYOUT# *   BASIC_0 #TAKE
+// #LAYOUT# *   *       #IGNORE
+
+// Just a compatibility jump - our routine is longer than original one
+
+	jmp MOVFA

c64/basic/math/bc0f.interop

@@ -0,0 +1,3 @@
+This is an important floating point math routine, documented in many places.
+
+XXX - try to find real-life example