--- a/src/math.inc	Thu Oct 11 21:06:29 2018 +0200
+++ b/src/math.inc	Thu Nov 22 19:47:26 2018 +0100
@@ -1,6 +1,6 @@
 ;=============================================================================
 ;
-;   File math.inc
+;   File math.inc									REFACTORED VERSION V2.99d
 ;
 ;
 ;   Copyright (c) 2011, JD Gascuel, HeinrichsWeikamp, all right reserved.
@@ -8,14 +8,38 @@
 ; HISTORY
 ;  2011-08-03 : [mH] moving from OSTC code
 
-	extern	convert_time
-	extern	div16
-	extern	sub16
-	extern	subU16
-	extern	mult16x16
-	extern	div16x16
-	extern	div32x16
-;	extern	isr_mult16x16
-	extern	isr_shift_C31
-	extern	isr_unsigned_mult16x16
-	extern	isr_signed_mult16x16
+	extern	convert_time			; converts hi:lo in minutes to hours (up:hi) and minutes (lo)
+									; also usable for conversion of seconds to minutes and seconds
+									; trashes xA, xB, xC
+
+	extern	div16					; divA:2 = divA:2 / 2^WREG
+									; trashes WREG
+
+	extern	mult16					; divA:2 = divA:2 * 2^WREG
+									; trashes WREG
+
+	extern	sub16					; sub_c:2 = sub_a:2 - sub_b:2	with SIGNED   values
+									; sets neg_flag if result is < 0
+									; trashes WREG
+
+	extern	subU16					; sub_c:2 = sub_a:2 - sub_b:2	with UNSIGNED values
+									; sets neg_flag if result is < 0
+									; trashes WREG
+
+	extern	mult16x16				; xC:4 = xA:2 * xB:2			with UNSIGNED values
+									; trashes PRODL, PRODH, WREG
+
+	extern	div16x16				; xC:2 = xA:2 / xB:2 with xA as remainder
+									; trashes xB, WREG
+
+	extern	div32x16				; xC:4 = xC:4 / xB:2 with xA as remainder
+									; trashes WREG
+
+	extern	isr_shift_C31			; 24 bit shift, repeated WREG times,
+									; dedicated to a specific usage
+
+	extern	isr_unsigned_mult16x16	; isr_xC = isr_xA * _isr_xB		with UNSIGNED values
+									; trashes PRODL, PRODH, WREG
+
+	extern	isr_signed_mult16x16	; isr_xC = isr_xA * _isr_xB		with SIGNED values
+									; trashes PRODL, PRODH, WREG