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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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Programs/print.asm
+83 -44
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@@ -5,55 +5,94 @@
; 10/27/2024
#Program
BRI Start ; Branch immediately to the start of the program.
printString:
CALL saveRegisters ; Store the registers so we can restore them later.
printLoop:
LDA ; Move the first character of the string into A.
BRA Return ; If A is NULL, the string is finished, so return.
OUTA 0x00 ; Output the character.
INCD ; Increment Data Pointer to the next character.
BRI printLoop ; Branch to the beginning of the loop.
BRI start ; Branch immediately to the start of the program.
lineFeed:
CALL saveRegisters ; Save the registers so they can be restored.
INIA 0x0A ; Load the character for linefeed into A.
OUTA 0x00 ; Output it.
CALL restoreRegisters
BRI Return ; We're done.
INIA 0x0A ; Load the character for linefeed into A.
OUTA 0x00 ; Output it.
RET ; Return to the caller.
saveRegisters: ; Subroutine for storing the registers.
PSHD ; Store the Data Pointer, push it to the stack.
SETD Registers ; Set the Data Pointer to the address for the registers.
STQ ; Store Q.
INCD ; Move to the next address.
STA ; Store A.
INCD ; Move to the next address.
STB ; Store B.
POPD ; Restore the Data Pointer.
RET ; Return to the caller.
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.
restoreRegisters:
PSHD ; Save the Data Pointer.
SETD Registers ; Set the Data Pointer to the registers address.
RSTB ; Set B to 0.
LDA ; Load the value for Q into A.
ADD ; Add 0 to move the value to Q.
INCD ; Move to the next register value.
LDA ; Load A with its value.
INCD ; Move to the next register value.
LDB ; Load B with its value.
POPD ; Restore the Data Pointer.
RET ; Return to the caller.
; Expects Data Pointer to be set to the one byte integer value to be printed in decimal form.
printDecimal:
LDA ; Load the value into A.
PSHA ; Save it onto the stack.
; Clear the buffer we're going to write into.
SETD DecimalValue ; Set the Data Pointer to the buffer.
RSTB ; Set B to 0.
STB ; Store it in the buffer.
INCD ; Increment to the tens place.
STB ; Store 0 in it.
INCD ; Increment to the hundred's place.
STB ; Store 0 in it.
INIB 0d10 ; Load 10 into B.
printDecimalLoopStart:
POPA ; Pop the value to A from the stack.
CCF ; Clear the Carry Flag.
SUB ; Subtract 10 from the value in A.
BRC getOnes ; If 10 is bigger than A, We're done looping and A contains the ones.
BRA getOnes ; If the value 0, we're also done.
; Otherwise, increment the tens place.
SETD DecimalValue ; Set the Data Pointer to the buffer.
INCD ; Increment to the tens place.
PSHQ ; Save the new value onto the stack.
LDA ; Load the number of tens into A.
INCA ; Increment it.
; Now check to see if there are ten tens and we need to carry to the hundreds.
CCF ; Clear the Carry Flag.
SUB ; Subtract 10 from A.
BRQ incrementHundreds ; If Q is 0, set the tens to 0 and increment the hundreds place.
STA ; Otherwise, store the value back to the tens place.
BRI printDecimalLoopStart ; and loop again.
incrementHundreds:
STQ ; Store 0 in the tens place.
INCD ; Increment the Data Pointer to the hundreds place.
LDA ; Load it into A.
INCA ; Increment it.
STA ; Store it back again.
BRI printDecimalLoopStart ; and Loop again.
getOnes:
SETD DecimalValue ; Set the Data Pointer to the ones place.
STA ; Store A in it.
; At this point we're done. We just need to print the digits with the printDecimalDigit subroutine.
INCD INCD ; Increment the Data Pointer twice to the hundreds place.
decimalCheckLoop:
LDA ; Load the value into A.
BRA checkTens ; If the hundreds are 0, skip printing their digit.
CALL printDecimalDigit ; Otherwise, print it.
DECD
CALL printDecimalDigit ; And the tens place, too.
BRI printOnes ; And finally, the ones.
checkTens:
DECD ; Decrement to the tens place.
LDA ; Load it into A.
BRA printOnes ; If the tens are zero, skip printing their digit, too.
CALL printDecimalDigit ; Otherwise, print it.
printOnes:
DECD ; Decrement to the ones place.
CALL printDecimalDigit ; Print it no matter what.
RET ; We're done, return to the caller.
Return:
CALL restoreRegisters ; Restore the registers.
RET ; Return to the caller.
printDecimalDigit: ; Expects Data Pointer to be set to the value to print.
LDA ; Load the value into A.
INIB 0x30 ; Load ASCII offset for numbers into B.
CCF ; Clear the Carry Flag.
ADD ; Add it to A.
OUTQ 0x00 ; Send it to the output.
RET ; Return from subroutine.
#Data
Registers: ; This is where saveRegisters stores the registers temporarily.
0x00 ; Q Register
0x00 ; A Register
0x00 ; B Register
; This is where printDecimal stores its result.
DecimalValue:
0x00 ; The ones place.
0x00 ; The tens place.
0x00 ; The hundreds place.