Add compute_ST

STATUS.md

@@ -196,7 +196,7 @@ Floating point mathematical routines - not official, but well known and broadly
 | `$AF7B`   | `compute_TI`           | NOT DONE |                                                    |
 | `$AF7E`   | not named yet          | NOT DONE |                                                    |
 | `$AF87`   | `set_FAC1_mantissa`    | DONE     |                                                    |
-| `$AF9A`   | `compute_ST`           | NOT DONE |                                                    |
+| `$AF9A`   | `compute_ST`           | DONE     |                                                    |
 | `$B1AA`   | `FACINX`               | NOT DONE | convert FAC1 to 16-bit signed integer              |
 | `$B1BF`   | `convert_FAC1_to_s16`  | NOT DONE |                                                    |
 | `$B391`   | `GIVAYF`               | PARTIAL  | not fully tested yet                               |

src/basic/math/af9a.compute_ST.s

@@ -10,8 +10,7 @@
 ; - https://www.c64-wiki.com/wiki/BASIC-ROM
 ;
 
-; XXX implement, test
-
 compute_ST:
 
-	+STUB_IMPLEMENTATION
+	lda IOSTATUS
+	jmp convert_A_to_FAC1

strings/4C3CBCA5

@@ -0,0 +1,3 @@
+JMP $BC3C + LDA fragment
+
+Jump to well known floating point function + fragment