Update cos_FAC1

STATUS.md

@@ -262,7 +262,7 @@ Floating point mathematical routines - not official, but well known and broadly
 | `$E097`   | `rnd_FAC1`             | DONE     |                                                    |
 | `$E09A`   | `rnd_A`                | DONE     |                                                    |
 | `$E0BE`   | `rnd_generate`         | DONE     |                                                    |
-| `$E264`   | `cos_FAC1`             | PARTIAL  | not fully tested yet                               |
+| `$E264`   | `cos_FAC1`             | DONE     | From the Microsoft BASIC, original name: COS       |
 | `$E26B`   | `sin_FAC1`             | PARTIAL  | not fully tested yet                               |
 | `$E2B4`   | `tan_FAC1`             | PARTIAL  | not fully tested yet                               |
 | `$E30E`   | `atn_FAC1`             | DONE     | From the Microsoft BASIC, original name: ATN       |

src/basic/math_trans/e264.cos_FAC1.s

@@ -2,9 +2,13 @@
 ;; #LAYOUT# *   BASIC_0 #TAKE
 ;; #LAYOUT# *   *       #IGNORE
 
-;
+; This file is under the MIT license, it contains code released by Microsoft Corporation.
+; See LICENSE for more information.
+
 ; Math package - cosine of FAC1 in radians
 ;
+; This is verified to be identical to the original Microsoft implementation where it was named COS
+;
 ; Adds pi/2 to FAC1 and falls through to the sine function
 ;
 ; See also:
@@ -18,10 +22,11 @@
 
 
 COS:
-    ldy #>const_HALF_PI
+
     lda #<const_HALF_PI
+    ldy #>const_HALF_PI
     jsr add_MEM_FAC1
-    
+ 
     ; FALLTHROUGH to SIN
 
 

tools/similarity.c

@@ -20,7 +20,7 @@ int matches[MAX_SIZE];
 
 int phase_mask[MAX_SIZE+MAX_SIZE];
 
-#define NUM_CHUNKS 10
+#define NUM_CHUNKS 11
 // Pairs of start, end memory addresses of known exact similarity with the open source Microsoft BASIC
 unsigned short microsoft_basic_chunks[NUM_CHUNKS * 2] = {
     0xB391, 0xB39D,
@@ -32,6 +32,7 @@ unsigned short microsoft_basic_chunks[NUM_CHUNKS * 2] = {
     0xBDB3, 0xBDC1,
     0xBDDD, 0xBF51,
     0xBFB4, 0xBFEC,
+    0xE264, 0xE26A,
     0xE30E, 0xE37A,
 };