More Programs

Added math library WIP. Added some other stuff.
2024-11-18 19:38:38 -05:00
parent fc2955cc21
commit bf7beec8ec
5 changed files with 150 additions and 3 deletions
@@ -0,0 +1,63 @@
+; A library of math subroutines for SplitBit.
+
+#Program
+
+int16add:
+    ; Add two two-byte unsigned integers.
+    ; Operands are stored in a four-byte array in the following order:
+    ; Operand A, high byte
+    ; Operand A, low byte
+    ; Operand B, high byte
+    ; Operand B, low byte
+    ; The result is stored by overwriting Operand A.
+    ; This subroutine expects the Data Pointer to be set to the start of the array.
+    ; After execution, this routine leaves the data pointer set to the high byte of the result.
+    ; If the addtion results in a carry, the carry flag will be set.
+  CCF             ; Clear the Carry Flag, just in case.
+  DPUP 0d03       ; Move to Operand B's low byte.
+  LDB             ; Load it to B.
+  DPDN 0d02       ; Move to Operand A's low byte.
+  LDA             ; Load it to A.
+  ADD             ; Add them together.
+  STQ             ; Store the result.
+  INCD            ; Go to Operand B's high byte.
+  LDB             ; Load it to B.
+  DPDN 0d02       ; Go to Operand A's high byte.
+  LDA             ; Load it to A.
+  ADD             ; Add them together.
+  STQ             ; Store the result.
+  RET             ; Return to the caller.
+
+int16sub:
+    ; Subtract two two-byte unsigned integers.
+    ; Operands are stored in a four-byte array in the following order:
+    ; Operand A, high byte
+    ; Operand A, low byte
+    ; Operand B, high byte
+    ; Operand B, low byte
+    ; Operand B is subtracted from Operand A and the result is stored by overwriting Operand A.
+    ; This subroutine expects the Data Pointer to be set to the start of the array.
+    ; After execution, this routine leaves the data pointer set to the high byte of the result.
+    ; If the addtion results in a carry, the carry flag will be set.
+  CCF             ; Clear the Carry Flag, just in case.
+  DPUP 0d03       ; Move to Operand B's low byte.
+  LDB             ; Load it to B.
+  DPDN 0d02       ; Move to Operand A's low byte.
+  LDA             ; Load it to A.
+  SUB             ; Subtract B from A.
+  STQ             ; Store the result.
+  INCD            ; Go to Operand B's high byte.
+  LDB             ; Load it to B.
+  DPDN 0d02       ; Go to Operand A's high byte.
+  LDA             ; Load it to A.
+  SUB             ; Subtract B from A.
+  STQ             ; Store the result.
+  RET             ; Return to the caller.
+
+#Data
+
+Int16operands:
+  0x00 ; Operand A high byte.
+  0x00 ; Operand A low byte.
+  0x00 ; Operand B high byte.
+  0x00 ; Operand B low byte.