implemented several simple floating point routines

2020-02-02 11:04:39 +01:00
1 parent 4673f825af
commit c62f53058e
@@ -1,17 +0,0 @@
-// #LAYOUT# STD *       #TAKE
-// #LAYOUT# *   BASIC_0 #TAKE
-// #LAYOUT# *   *       #IGNORE
-
-//
-// Math package - copy FAC2 to FAC1
-//
-// See also:
-// - [CM64] Computes Mapping the Commodore 64 - page 115
-// - https://www.c64-wiki.com/wiki/Floating_point_arithmetic
-// - https://codebase64.org/doku.php?id=base:kernal_floating_point_mathematics
-//
-
-// XXX provide implementation
-
-MOVEF:
-	STUB_IMPLEMENTATION()
@@ -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 mov_r_FAC1_TMP2
@@ -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 mov_r_FAC1_TMP1
@@ -0,0 +1,3 @@
+This is an important floating point math routine, documented in many places.
+
+XXX - try to find real-life example
@@ -0,0 +1,20 @@
+// #LAYOUT# STD *       #TAKE
+// #LAYOUT# *   BASIC_0 #TAKE
+// #LAYOUT# *   *       #IGNORE
+
+//
+// Math package - move FAC1 (rounds) to memory variable
+//
+// Input:
+// - FORPNT ($49/$4A) - variable address
+//
+// See also:
+// - https://www.c64-wiki.com/wiki/BASIC-ROM
+//
+
+mov_r_FAC1_VAR:
+
+	ldy #FORPNT+1
+	ldx #FORPNT+0
+
+	// FALLTROUGH to mov_r_FAC1_MEM
@@ -0,0 +1,3 @@
+This is an important floating point math routine, documented in many places.
+
+XXX - try to find real-life example
@@ -3,12 +3,11 @@
 // #LAYOUT# *   *       #IGNORE

 //
-// Math package - copy FAC1 to memory location, rounds if asked
+// Math package - copy FAC1 to memory location, do not round
 //
 // Input:
 // - .X - address low byte
 // - .Y - address high byte
-// - $70 - if MSB is set performs rouding
 //
 // Output:
 // - .A - FAC1 exponent
@@ -18,7 +17,9 @@
 // - https://codebase64.org/doku.php?id=base:kernal_floating_point_mathematics
 //

-// XXX provide implementation
+mov_r_FAC1_MEM:
+	
+	// Start by rounding FAC1

-MOVFM2:
-	STUB_IMPLEMENTATION()
+	jsr round_FAC1
+	jmp mov_FAC1_MEM
@@ -0,0 +1,3 @@
+This is an important floating point math routine, documented in many places.
+
+XXX - try to find real-life example
@@ -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 mov_FAC2_FAC1
@@ -14,7 +14,7 @@
 // - https://www.c64-wiki.com/wiki/Floating_point_arithmetic
 //

-movr_FAC1_FAC2:
+mov_r_FAC1_FAC2:

 	// First round FAC1
 	jsr round_FAC1
@@ -0,0 +1,77 @@
+// #LAYOUT# STD *       #TAKE
+// #LAYOUT# *   BASIC_0 #TAKE
+// #LAYOUT# *   *       #IGNORE
+
+//
+// Math package - copy FAC1 to memory location, do not round
+//
+// Input:
+// - .X - address low byte
+// - .Y - address high byte
+//
+// Output:
+// - .A - FAC1 exponent
+//
+// See also:
+// - https://www.c64-wiki.com/wiki/Floating_point_arithmetic
+// - https://codebase64.org/doku.php?id=base:kernal_floating_point_mathematics
+//
+
+mov_FAC1_MEM:
+
+	// Checked in the available documentation:
+	// - https://www.c64-wiki.com/wiki/Floating_point_arithmetic
+	// - https://www.lemon64.com/forum/viewtopic.php?t=67576&sid=d41e77cdddd28d6f9c9d52ce5b4e8dc3
+	// that $22/$23 (INDEX+0 and INDEX+1) are at least sometimes used for pointer storage.
+	// Confirmed by experimenting with original ROM that this is the case here too.
+
+	sty INDEX+1
+	stx INDEX+0
+
+	ldy #$00
+
+	// Copy exponent
+
+	lda FAC1_exponent
+	sta (INDEX), y
+	beq mov_FAC1_MEM_end               // for 0 no need to copy anything more
+
+	// Copy first byte of mantissa
+
+	iny
+	lda FAC2_mantissa+3
+	sta (INDEX), y
+
+	// Copy the sign       XXX try to optimize this part
+
+	lda FAC1_sign
+	bne !+
+
+	lda FAC2_mantissa+3
+	and #$7F
+	sta (INDEX), y
+!:
+	// Copy remaining parts of mantissa
+
+	iny
+	lda FAC2_mantissa+2
+	sta (INDEX), y
+
+	iny
+	lda FAC2_mantissa+1
+	sta (INDEX), y
+
+	iny
+	lda FAC2_mantissa+0
+	sta (INDEX), y
+
+	// Checked, that mov_FAC1_MEM works on real ROM too (at $BBD7),
+	// and clears FACOV in a similar way as mov_FAC1_FAC2 does (not surprising)
+
+	ldy #$00
+	sty FACOV
+
+mov_FAC1_MEM_end:
+
+	lda FAC1_exponent
+	rts
@@ -0,0 +1,49 @@
+// #LAYOUT# STD *       #TAKE
+// #LAYOUT# *   BASIC_0 #TAKE
+// #LAYOUT# *   *       #IGNORE
+
+//
+// Math package - copy FAC2 to FAC1
+//
+// Output (found by experimentation):
+// - .A - FAC1 exponent
+// - .X - always 0
+//
+// Preserves:
+// - .Y
+//
+// See also:
+// - [CM64] Computes Mapping the Commodore 64 - page 115
+// - https://www.c64-wiki.com/wiki/Floating_point_arithmetic
+// - https://codebase64.org/doku.php?id=base:kernal_floating_point_mathematics
+//
+
+mov_FAC2_FAC1:
+
+	// Copy the mantissa
+
+	lda FAC2_mantissa+3
+	sta FAC1_mantissa+3
+	lda FAC2_mantissa+2
+	sta FAC1_mantissa+2
+	lda FAC2_mantissa+1
+	sta FAC1_mantissa+1
+	lda FAC2_mantissa+0
+	sta FAC1_mantissa+0
+
+	// Copy the sign
+
+	lda FAC2_sign
+	sta FAC1_sign
+
+	// Copy the exponent
+
+	lda FAC2_exponent
+	sta FAC1_exponent
+
+	// Clear FACOV
+
+	ldx #$00
+	stx FACOV
+
+	rts
@@ -0,0 +1,18 @@
+// #LAYOUT# STD *       #TAKE
+// #LAYOUT# *   BASIC_0 #TAKE
+// #LAYOUT# *   *       #IGNORE
+
+//
+// Math package - store FAC1 (rounds) in TEMPF1
+//
+// See also:
+// - https://www.c64-wiki.com/wiki/BASIC-ROM
+// - https://sta.c64.org/cbm64basconv.html
+//
+
+mov_r_FAC1_TMP1:
+
+	ldy #$00
+	ldx #$5C
+
+	jmp mov_r_FAC1_MEM
@@ -0,0 +1,18 @@
+// #LAYOUT# STD *       #TAKE
+// #LAYOUT# *   BASIC_0 #TAKE
+// #LAYOUT# *   *       #IGNORE
+
+//
+// Math package - store FAC1 (rounds) in TEMPF2
+//
+// See also:
+// - https://www.c64-wiki.com/wiki/BASIC-ROM
+// - https://sta.c64.org/cbm64basconv.html
+//
+
+mov_r_FAC1_TMP2:
+
+	ldy #$00
+	ldx #$57
+
+	jmp mov_r_FAC1_MEM