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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
+80 -41
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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.
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.
restoreRegisters:
PSHD ; Save the Data Pointer.
SETD Registers ; Set the Data Pointer to the registers address.
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.
; 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.
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.
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.
Programs/printDecimalTest.asm
+31
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@@ -0,0 +1,31 @@
; Tests for the printDecimal subroutine.
#Include print.asm
#Program
start:
INIB 0xFF ; Load 255 into B.
loop:
SETD MyDecimal ; Set D to our decimal.
SUB
CCF ; Clear the Carry Flag.
CALL printDecimal ; Print the value.
LDA ; Load the value into A.
INCA ; Increment it.
STA ; Store it again.
SETD Space
CALL printString ; Print a space between the the numbers.
BRQ end ; If Q is zero, we're done.
BRI loop ; Branch back to the start of the loop.
end:
CALL lineFeed
HALT
#Data
MyDecimal:
0x00
Space:
" "
Programs/printDigitTest.asm
+24
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@@ -0,0 +1,24 @@
#Include print.asm
#Program
start:
INIB 0d10
SETD byte
loop:
CALL printDecimalDigit
LDA
INCA
STA
SUB
BRQ end
CALL lineFeed
BRI loop
end:
CALL lineFeed
HALT
#Data
byte:
0x00
Programs/printHello.asm
+18 -6
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@@ -8,13 +8,25 @@
#Include print.asm
#Program
Start:
SETD myString ; Set the Data Pointer to the string we want to print.
CALL printString ; Call the subroutine.
CALL lineFeed ; Call the linefeed subroutine.
HALT ; Stop the CPU.
start:
SETD MyString ; Set the Data Pointer to the start of MyString.
CALL printString ; Call the string printing subroutine.
CALL lineFeed ; Call the line feed subroutine to end the line.
SETD MyDecimal ; Set the Data Pointer to the value to print as a decimal.
CALL printDecimal ; Call the decimal printing subroutine.
SETD MyMessage ; Set the Data Pointer to another string.
CALL printString ; Call the string printing subroutine again.
CALL lineFeed ; Call the line feed subroutine to end the line.
HALT ; Stop the program.
#Data
myString:
MyString:
"Hello, World! "
MyDecimal:
0d42
MyMessage:
" is the great answer."
Source/Assembler/assembly.c
+2
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@@ -29,6 +29,7 @@ Instruction instruction_set[] = {
{0x13, "BRB"},
{0x14, "CALL"},
{0x15, "RET"},
{0x16, "BRC"},
// Register Operations:
{0x20, "RSTA"},
{0x21, "RSTB"},
@@ -40,6 +41,7 @@ Instruction instruction_set[] = {
{0x27, "LDB"},
{0x28, "INIA"},
{0x29, "INIB"},
{0x2F, "CCF"},
// Stack Operations:
{0x30, "PSHQ"},
{0x31, "PSHA"},
Source/Emulator/cpu.c
+50 -8
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@@ -121,16 +121,55 @@ uint8_t executeOperation(uint8_t Instruction, CPURegisters *cpu) {
cpu->StackPointer--;
cpu->Data[cpu->StackPointer] = (cpu->ProgramCounter >> 8) & 0xFF;
cpu->StackPointer--;
// Push the Data Pointer to the Stack.
// Order, low byte, high byte
cpu->Data[cpu->StackPointer] = cpu->DataPointer & 0xFF;
cpu->StackPointer--;
cpu->Data[cpu->StackPointer] = (cpu->DataPointer >> 8) & 0xFF;
cpu->StackPointer--;
// Push Q to the Stack.
cpu->Data[cpu->StackPointer] = cpu->Q;
cpu->StackPointer--;
// Push B to the Stack.
cpu->Data[cpu->StackPointer] = cpu->B;
cpu->StackPointer--;
// Push A to the Stack.
cpu->Data[cpu->StackPointer] = cpu->A;
cpu->StackPointer--;
// Perform a Generic Branch to the Address.
genericBranch(cpu);
break;
case 0x15:
// RET - Return from subroutine, restore the Program Counter from the Stack.
// POPP - Pop Data to the Program Counter
// RET - Return from subroutine, restore the registers and set the Program Counter to the Return Address.
// Pop A from the Stack.
cpu->StackPointer++;
cpu->A = cpu->Data[cpu->StackPointer];
// Pop B from the Stack.
cpu->StackPointer++;
cpu->B = cpu->Data[cpu->StackPointer];
// Pop Q from the Stack.
cpu->StackPointer++;
cpu->Q = cpu->Data[cpu->StackPointer];
// Pop the Data Pointer from the Stack.
cpu->StackPointer++;
cpu->DataPointer = (uint16_t)cpu->Data[cpu->StackPointer] << 8;
cpu->StackPointer++;
cpu->DataPointer |= (uint16_t)cpu->Data[cpu->StackPointer];
// Pop the Return Address from the Stack.
cpu->StackPointer++;
cpu->ProgramCounter = (uint16_t)cpu->Data[cpu->StackPointer] << 8;
cpu->StackPointer++;
cpu->ProgramCounter = cpu->ProgramCounter | (uint16_t)cpu->Data[cpu->StackPointer];
cpu->ProgramCounter += 2; // Because it needs to skip over the address when it returns.
// Add 2 to the Program Counter to skip over the address when it returns.
cpu->ProgramCounter += 2;
break;
case 0x16:
// BRC - Do an immediate branch is the Carry Flag is set.
if (cpu->Status & 0x01) {
genericBranch(cpu);
} else {
cpu->ProgramCounter+=2;
}
break;
//
// 2x - Register Operations:
@@ -177,6 +216,10 @@ uint8_t executeOperation(uint8_t Instruction, CPURegisters *cpu) {
cpu->ProgramCounter++;
cpu->B = cpu->Program[cpu->ProgramCounter];
break;
case 0x2F:
// CCF - Clear the Carry Flag.
cpu->Status &= ~0x01;
break;
//
// 3x - Stack Operations:
//
@@ -195,9 +238,8 @@ uint8_t executeOperation(uint8_t Instruction, CPURegisters *cpu) {
cpu->Data[cpu->StackPointer] = cpu->B;
cpu->StackPointer--;
break;
break;
case 0x33:
// PSHD - Push the Data Pointer to the Stack.
// PSHD - Push the Data Pointer Address to the Stack.
// Order, low byte, high byte
cpu->Data[cpu->StackPointer] = cpu->DataPointer & 0xFF;
cpu->StackPointer--;
@@ -205,18 +247,18 @@ uint8_t executeOperation(uint8_t Instruction, CPURegisters *cpu) {
cpu->StackPointer--;
break;
case 0x34:
// POPA - Pop Data to A.
// POPA - Pop A from the Stack.
cpu->StackPointer++;
cpu->A = cpu->Data[cpu->StackPointer];
break;
case 0x35:
// POPB - Pop Data to B.
// POPB - Pop B from the Stack.
cpu->StackPointer++;
cpu->B = cpu->Data[cpu->StackPointer];
break;
case 0x36:
// POPD - Pop Data to the Data Pointer
// POPD - Pop Data Address from the Stack.
cpu->StackPointer++;
cpu->DataPointer = (uint16_t)cpu->Data[cpu->StackPointer] << 8;
cpu->StackPointer++;
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!"
```
SplitBit Programming Manual.md
+28 -38
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@@ -29,17 +29,18 @@ Hex Code | Mnemonic | Description
07 | NOTA | Bitwise inversion of A, the result is stored in Q.
08 | NOTB | Bitwise inversion of B, the result is stored in Q.
### Branch Operations: 4 Instructions
### Branch Operations: 7 Instructions
Hex Code | Mnemonic | Description
-- | -- | --
10 | BRI | Branch Immediately. Loads the immediate next two bytes of Program Memory into the Program Counter, first the most significant byte, then the least.
11 | BRQ | Branch on Q. If Q is zero, loads the immediate next two bytes of Program Memory into the Program Counter.
12 | BRA | Branch on A. If A is zero, loads the immediate next two bytes of Program Memory into the Program Counter.
13 | BRB | Branch on B. If B is zero, loads the immediate next two bytes of Program Memory into the Program Counter.
14 | CALL | Push the Program Counter to the Stack, loads the immediate next two bytes of Program Memory into the Program Counter.
15 | RET | Restores the Program Counter from the Stack, used to return from subroutines.
14 | CALL | Stores all the registers to the Stack, A, B, Q, the Data Pointer, and the Program Counter, then performs an immediate branch.
15 | RET | Restores all registers from the Stack, then immediately branches to the Return Address by setting the Program Counter to the next instruction after the last CALL.
16 | BRC | Branch if Carry is set.
### Register Operations: 6 Instructions
### Register Operations: 11 Instructions
| Hex Code | Mnemonic | Description |
| -------- | -------- | ------------------- |
| 20 | RSTA | Resets A to 0. |
@@ -52,8 +53,9 @@ Hex Code | Mnemonic | Description
| 27 | LDB | Loads Data to B via the Data Pointer.
| 28 | INIA | Loads the next byte of Program Memory to A. |
| 29 | INIB | Loads the next byte of Program Memory to B. |
| 2F | CCF | Clears the Carry Flag. |
### Stack Operations: 9 Instructions
### Stack Operations: 7 Instructions
Hex Code | Mnemonic | Description
-- | -- | --
30 | PSHQ | Stores Q into Data Memory at the location referenced by the Stack Pointer then decrements the Stack Pointer.
@@ -64,7 +66,7 @@ Hex Code | Mnemonic | Description
35 | POPB | Reads the location referenced by the Stack Pointer from Data Memory into B then increments the Stack Pointer.
36 | POPD | Restores the Program Counter from the top two bytes in the stack, increments the Stack Pointer by two.
### Data Operations: 7 Instructions
### Data Operations: 8 Instructions
Hex Code | Mnemonic | Description
-- | -- | --
40 | INCD | Increments the Data Pointer.
@@ -103,38 +105,26 @@ The current implementation has Input 0 and Output 0 hooked to stdout and stdin r
### Example Program: Hello World
```
; Hello World for SplitBit CPU
; First, we define the string in Data Memory.
Data:
0000 0x48 ; 'H'
0001 0x65 ; 'e'
0002 0x6C ; 'l'
0003 0x6C ; 'l'
0004 0x6F ; 'o'
0005 0x2C ; ','
0006 0x20 ; ' '
0007 0x57 ; 'W'
0008 0x6F ; 'o'
0009 0x72 ; 'r'
000A 0x6C ; 'l'
000B 0x64 ; 'd'
000C 0x32 ; '!'
000D 0x0A ; This is a linefeed, it's equivalent to putting '\n' in a string in C.
000E 0x00 ; Zero terminates the string.
; 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.
; Next, we'll create a loop that outputs each byte of our string to Output 0, the text console.
Program:
0000 LDA 0x42 ; Load the first byte of the string into A.
0001 BRA 0x12 ; If A is zero, branch out of the loop.
0002 0x00 0x00 ; The high byte of the branch.
0003 0x0A 0x0A ; The low byte of the branch.
0004 OUTA 0xD1 ; Output the value in A.
0005 0x01 0x00 ; The Output Port to use.
0006 INCD 0x40 ; Increment the Data Pointer to the next byte of the string.
0007 BRI 0x10 ; Branch immediately to the start of the loop.
0008 0x00 0x00 ; The high byte of the branch address.
0009 0x00 0x00 ; The low byte of the branch address.
000A HALT 0xFF ; The end of the program.
#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.
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.
#Data
"Hello, World!"
```
### Structure of a SplitBit Binary File:
@@ -143,5 +133,5 @@ The Program and Data values are both stored in a single file for loading into th
Here's an example hex dump of the hello world program stored in the proper format:
```
50 52 47 00 0A 42 12 00 0A D1 00 40 10 00 00 FF 44 41 54 00 0E 48 65 6C 6C 6F 2C 20 57 6F 72 6C 64 21 0A 00
50 52 47 00 0F 26 12 00 0A D1 00 40 10 00 00 28 0A D1 00 FF 44 41 54 00 0E 48 65 6C 6C 6F 2C 20 57 6F 72 6C 64 21 00
```