Add int to float conversions

src/basic/math/bc44.convert_i16_to_FAC1.s

@@ -0,0 +1,29 @@
+;; #LAYOUT# STD *       #TAKE
+;; #LAYOUT# X16 BASIC_0 #TAKE-OFFSET 2000
+;; #LAYOUT# *   BASIC_0 #TAKE
+;; #LAYOUT# *   *       #IGNORE
+
+;
+; Math package - Convert signed 16-bit integer to floating point
+;
+; - https://codebase64.org/doku.php?id=base:kernal_floating_point_mathematics
+; - https://www.c64-wiki.com/wiki/GIVAYF (which calls this function)
+;
+; Convert the signed 16-bit integer in FAC1 mantissa ($62:$63)
+; into a floating point number in FAC1
+
+; NOTE:
+; According to https://c64os.com/post/floatingpointmath at $BC49
+; Assume FAC1_mantissa+0 and +1. X=exponent and C=0 if negative and C=1 if positive
+
+convert_i16_to_FAC1:
+    ldx #$90
+    jsr carry
+
+    jmp convert_i16_expsign_to_FAC1   ; This should be at $BC49 (see note above)
+
+
+carry:
+    lda FAC1_mantissa+1
+    cmp #$80                    ; Copy sign into carry
+    rts