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Added new instructions.

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Added CCF - Clear Carry Flag
Added BRC - Branch on Carry Flag
Improved CALL and RET - All registers but status now saved and restored.
This commit is contained in:
Anachronaut
2024-10-29 21:04:03 -04:00
committed by GitHub
parent f9308338c4
commit a58fb3d694
8 changed files with 255 additions and 112 deletions
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SplitBit Assembler Manual.md
+18 -15
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@@ -16,11 +16,11 @@ The assembler will accept:
Labels may be a string of up to 32 alphanumeric characters that must end with a semicolon, ':'.
```
ProgramStart:
programStart:
LoopStart:
loopStart:
ErrorHandler01:
errorHandler01:
```
@@ -36,25 +36,28 @@ SplitBit programs may have a Data Segment. You may define the start of the data
## An Example SplitBit Assembly Program:
```
; This is a basic hello world program for the SplitBit CPU.
; We'll create a loop that outputs each byte of our string to Output 0, the text console.
; This is a slightly more advanced hello world program that demonstrates some SplitBit programming conventions.
#Program
Start:
LDA ; Load a byte of the string into A.
BRA End ; If A is zero, branch out of the loop.
OUTA 0x00 ; Output the value in A to Port 0, the text console.
INCD ; Increment the Data Pointer to the next byte of the string.
BRI Start ; Branch immediately to the start of the loop.
start: ; By uninforced convention, Program Labels start with a lowercase letter.
SETD HelloString ; Set the Data Pointer to the address of the string.
CALL printString ; Call the string printing subroutine.
HALT ; End the program.
End:
INIA 0x0A ; We'll load a linefeed into A and output it to make it look nice.
OUTA 0x00 ; Output it to the text console.
HALT ; Terminate the program.
; This is a reusable subroutine that could be includedd in other programs.
printString: ; Expects Data Pointer to be set to the beginning of the string to be printed.
LDA ; Move the first character of the string into A.
BRA printDone ; If A is NULL, the string is finished, so return.
OUTA 0x00 ; Output the character.
INCD ; Increment Data Pointer to the next character.
BRI printString ; Branch to the beginning of the loop.
printDone:
RET ; Return to the caller.
#Data
HelloString: ; By uninforced convention, Data Labels start with a capital letter.
"Hello, World!"
```