Remove files that aren't notes

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n loewen 2023-08-29 08:40:36 -04:00
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.gitmodules vendored
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[submodule "src/argparser"]
path = src/argparser
url = https://git.nloewen.com/n/argv-parser.git

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# Cardiograph issues
## Open
### #1 - Improve CLI interface
I'm thinking of an interface like this...
$ ./cpu.js -mc code.bin
$ ./cpu.js code.asm
$ ./cpu.js --debug code.asm
Full list of flags I want:
-d --debug
-s --singlestep
-p --prettydisplay
-mc --machinecode
### #2 - Startup: Execute `JMP $FF`
See [2023-08-24](../notes/2023-08-24--dev-notes.md#cpu-start-up)
... say that there's a 1-byte ROM at $FF.
- `00-19` - display (5x5)
- `1A ` - pointer to display memory
- `1B ` - keypad: value of latest key pressed
- `1C ` - reserved for future use (bank switching flag)
- `1D ` - initial IP
- `1D-FE` - free
- `FF ` - ROM (unwriteable) - pointer to initial IP
- store `$1D` at `$FF`
- make CPU execute `JMP $FF` on startup
- make ROM unwriteable
More step-by-step:
- Change memory from a Uint8Array to a regular array,
and make every entry { number | { type: 'ROM', value: number }}
- Store ROM as an object in machine.config.js
- Load ROM data into memory at CPU startup (`startCPU(RAM, ROM)`)
## Closed

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# To do — Summary
This is a quick todo list.
For extended commentary, see [issues](issues.md).
## Open
### Todo
- Finish WIP on run-cli arg parsing
- Pass CYCLE_COUNT as a cli arg
- (cpu) !! Fix overflow flag
- Add a flag for bank-switching to the ~zero-page
- Remove run-scripts and add the ability to run `./cpu.js` and `./assembler.js` directly -- cf. [#1](issues.md#1---improve-cli-interface)
- [fix] (cpu) Make single-stepping work with simulated keypad
### Features
- (cpu) allow arrow keys, too
- [fix] (cpu) Execute `JMP $FF` on startup / Implement ROM — see [#2](issues.md#2---startup-execute-jmp-ff)
- (assembler) Validate labels
- (assembler) Extract debugging to its own module
- (cpu) Consider adding a VIP-style keypad-based machine code monitor
- (cpu) Add a mode that prints the display as text, but still animates
- (cpu) Allow running pre-compiled machine code
- (cpu) DRY out addition and subtraction
- [Extended system (secret bonus operations)](../notes/2023-08-07--dev-notes.md)
- (research) Review CHIP-8
- read about the spec / ISA
- read these, and add them to the bibliography:
- Steve Losh: https://stevelosh.com/blog/2016/12/chip8-input/
- https://tonisagrista.com/blog/2021/chip8-spec/
### Documentation
- Improve docs for flags register
### Testing
- Display (hex) numbers
- Greater than
- Minimal LOGO-ish interpreter for turtle graphics
## Closed
- 2023-08-26 - [fix] (logging) - 'undefined operand' situation is caused by assembling to an initial IP of $1C, which is an odd number
- (assembler) Pass asm line thru to cpu to print when debugging
## Abandoned
- (assembler) Return pure machine code when printing to stdout (and not in debug mode)

175
readme.md
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# Cardiograph Mark I — simulator for an imaginary computer
## Dependencies
- Node.js
- readline-sync
## Run
### Assemble
Hex output:
```./run-assembler run source_code.asm```
Binary output:
```./run-assembler runbin source_code.asm```
Verbose debugging output (hex):
```./run-assembler debug source_code.asm```
### Assemble and run
With animated display of screen memory:
```./run-cpu run source_code.asm```
With verbose debugging output:
```./run-cpu debug source_code.asm```
With single stepping + pretty-printed display:
```./run-cpu step source_code.asm```
With single stepping + verbose debugging output:
```./run-cpu stepdebug source_code.asm```
## Registers and Flags
- `A` - accumulator
- `IP` - instruction pointer (aka program counter)
- `FLAGS` - flags: **O**verflow, **N**egative, **Z**ero, **C**arry
- in machine language, each flag is given a number:
- O = 3
N = 2
Z = 1
C = 0
- (bitwise, `0000 = ONZC`)
## Instruction set
### Operations
```
Hex Mnem. Operand Effect
00 END (ignored) Halt CPU
01 STO literal # mem[lit#] = A
02 STO address mem[mem[addr]] = A
03 LDA literal # A = lit#
04 LDA address A = addr
05 ADD literal # A = A + lit#
06 ADD address A = A + mem[addr]
07 SUB literal # A = A - lit#
08 SUB address A = A - mem[addr]
09 HOP literal # If A == lit#, skip next op (IP += 4)
0A HOP address If A == mem[addr], skip next instruction (IP += 4)
0B JMP literal # IP = lit#
0C JMP address IP = mem[addr]
0D FTG literal # Toggle flag, where flag number == lit#
0E FHP literal # Skip next op if flag is set, where flag number == lit#
0F NOP (ignored) None
```
- Instructions are two bytes long:
one byte for the opcode, one for the operand
### Effects on memory, flags, registers
```
op mem flags IP
END +2
NOP +2
STO w +2
LDA r NZ +2
ADD ONZC +2
SUB ONZC +2
HOP +2/+4
JMP arg
FTG ONZC +2
FHP ONZC +2/+4
STO r,w +2
LDA r,r NZ +2
ADD r ONZC +2
SUB r ONZC +2
HOP r +2/+4
JMP r arg
FTG r ONZC +2
FHP r ONZC +2/+4
```
## CPU start-up
When starting up, the CPU executes a `JMP $FF`.
Put differently: it starts executing instructions at the address contained in `$FF`.
## Cardiograph memory map
- `00-19` - display (5x5)
- `1A ` - pointer to display memory
- `1B ` - keypad: value of latest key pressed
- `1C ` - reserved for future use (bank switching flag)
- `1D ` - initial IP
- `1D-FE` - free
- `FF ` - ROM (unwriteable) pointer to initial IP (not yet implemented)
## Peripherals
### Keypad
The value of the latest keypress on a hex keypad is stored at `$1B`.
The keypad uses the same layout as the COSMAC VIP (and CHIP-8). The CPU simulator maps those keys onto a Qwerty set:
```
1 2 3 C 1 2 3 4
4 5 6 D Q W E R
7 8 9 E A S D F
A 0 B F Z X C V
hex pad simulator
```
The arrow keys are also mapped onto the hex keypad:
```
5 ↑
7 8 9 ← ↓ →
hex pad simulator
```
## Assembly language
ADD $01 ; comments follow a `;`
ADD $FF ; this is direct addressing
ADD ($CC) ; this is indirect addressing
END ; END and NOP don't require operands
; (the assembler will fill in a default value of 0)
@subroutine ; create a label
ADD $01 ; (it must be on the line before the code it names)
ADD $02
JMP @subroutine ; use a label as operand
; the label will be replaced with
; the address of the label
#foo $FF ; define a constant
; (must be defined before it is referenced)
ADD #foo ; use a constant as an operand
LDA * ; `*` is a special label referencing the memory address
; where the current line will be stored after assembly
- Hexadecimal numbers are preceded by a `$`
- Whitespace is ignored

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const { logMemory, num2hex } = require('./logging.js');
const {
INITIAL_IP_ADDRESS,
DISPLAY_ADDR,
POINTER_TO_DISPLAY,
} = require('./machine.config.js');
// 1 = verbose
// 2 = what i'm currently focusing on
// 3 = always print
// 4 = silent
const DEBUG_LEVEL = 2;
let DEBUG; // Turn debugging on/off -- set by assemble()
/**
* @param {string} assemblyCode
* @param {Boolean} [debug = false]
**/
exports.assemble = (assemblyCode, debug = false) => {
DEBUG = debug;
return decodeInstructions(assemblyCode);
}
// Configure pseudo-ops:
const ASM_IP_LABEL = '*';
const ASM_CONSTANT_PREFIX = '#';
const ASM_LABEL_PREFIX = '@';
const mnemonicsWithOptionalArgs = ['end', 'nop'];
const mnemonics2opcodes = {
end: { direct: 0, indirect: 0 },
sto: { direct: 1, indirect: 2 },
lda: { direct: 3, indirect: 4 },
add: { direct: 5, indirect: 6 },
sub: { direct: 7, indirect: 8 },
hop: { direct: 9, indirect: 10 },
jmp: { direct: 11, indirect: 12 },
ftg: { direct: 13, indirect: 13 },
fhp: { direct: 14, indirect: 14 },
nop: { direct: 15, indirect: 15 },
};
/**
* @typedef {('code'|'comment'|'blank')} SourceLineType
**/
/**
* @typedef {Object} SourceLineInfo
* @property {number} number - line number
* @property {string} source - source text
* @property {string} sanitized - source text, with comments and whitespace removed
* @property {SourceLineType} type - line type
* @property {string} [operation] - For code: the first non-whitespace chunk
* @property {string} [argument] - For code: the second non-whitespace chunk, if there is one
* @property {string} [extraArgument] - For code: the third non-whitespace chunk, if there is one
**/
/**
* @param {string} source
* @returns {Array<SourceLineInfo>}
**/
function preparseSourceCode(source) {
let lines = source.split(/\n/); // returns an array of lines
const isLineBlank = (l) => { return stripWhitespaceFromEnds(l).length === 0 ? true : false };
const isLineComment = (l) => { return stripWhitespaceFromEnds(l).startsWith(';') };
/**
* @param {string} l
* @returns {SourceLineType}
**/
const getLineType = (l) => {
if (isLineBlank(l)) return 'blank';
if (isLineComment(l)) return 'comment';
return 'code';
}
return lines.map((line, index) => {
dbg(1, ` in: ${line}`);
let info = {
number: index + 1,
source: line,
sanitized: stripWhitespaceFromEnds(stripComments(line)),
type: getLineType(line),
};
dbg(1, `${info.number} - ${info.type}: ${info.sanitized}`);
dbg(1, ``);
if (info.type === 'code') {
const op_arg_array = info.sanitized.split(/\s+/); // split line into an array of [op, arg, extra_arg]
if (op_arg_array[0] !== 'undefined') {
info.operation = op_arg_array[0];
}
if (op_arg_array.length === 2) {
info.argument = op_arg_array[1];
}
if (op_arg_array.length === 3) {
info.argument = op_arg_array[1];
info.extraArgument = op_arg_array[2];
}
// If there's too many arguments, throw an error
// NB. there's a special case:
// lines with the ASM_IP_LABEL can take an extra argument
let maxArgs = 2;
if (op_arg_array.length > 2 && op_arg_array[1].startsWith(ASM_IP_LABEL)) {
maxArgs = 3;
}
if (op_arg_array.length > maxArgs) {
console.error();
console.error(`Error: Too many arguments`);
console.error(` at line ${info.number}`);
process.exit();
}
}
return info;
});
}
/**
* @param {string} arg
* @returns {number}
**/
function decodeNumericOp(arg) {
if (arg.startsWith("$")) return hex2num(arg.replace("$", ""));
return parseInt(arg);
}
/**
* @param {string} op
* @param {object} labels // TODO document better
* @param {number} IP
* @returns {Array<string>} - array of labels
**/
function handleLabelDefinition(op, IP, labels) {
let label = op.substring(1); // strip label prefix
if (label in labels) {
labels[label].pointsToByte = IP;
} else {
labels[label] = {
pointsToByte: IP,
bytesToReplace: [],
};
}
dbg(1, ` Label definition:`);
dbg(1, ` Points to byte: ${labels[label].pointsToByte}`);
dbg(1, ` Bytes to replace: ${labels[label].bytesToReplace}`);
dbg(1, ` IP: $${num2hex(IP)}, new code: none`);
dbgGroupEnd(1, 'Input line');
return labels;
}
/**
* @param {string} op
* @param {string} arg
* @param {number} IP
* @returns {Array<string>} - array of constants
**/
function handleConstantDefinitions(op, arg, IP, constants) {
let constantName = op.substring(1); // strip '>'
let constantValue = arg;
if (constantValue === ASM_IP_LABEL) {
constantValue = IP.toString();
}
constants[constantName] = constantValue;
dbg(1, '');
dbg(1, `Constants:`);
dbg(1, constants);
dbg(1, '');
return constants;
}
/**
* Assemble source code.
*
* If the source doesn't explicitly set an address to assemble to,
* it will be assembled to the default intial value of the IP,
* as specified in `machine.config.js`.
* @param {string} source - Assembly source to decode
* @return {{ debugInfo: Object, machineCode: Uint8Array }};
**/
function decodeInstructions(source) {
dbg(1, 'Pre-parsing...');
let lines = preparseSourceCode(source);
dbg(1, '');
dbg(1, 'Done pre-parsing.');
dbg(1, '');
dbg(1, 'Assembling...');
// Figure out where to start assembly...
/** @type {number} IP - Destination addr for the next line **/
let IP;
// Check if the source code explicitly sets an address to assemble at
// by including a `* [addr]` as the first (non-blank, non-comment) line
let idOfFirstLineWithCode = lines.findIndex((el) => el.type === 'code');
if (lines[idOfFirstLineWithCode].operation.startsWith(ASM_IP_LABEL)) {
IP = parseInt(lines[idOfFirstLineWithCode].argument);
} else {
IP = INITIAL_IP_ADDRESS;
}
// Initialize arrays to collect assembled code
/** @type {Array<number>} - Assembled source code, as an array of bytes **/
let machineCode = new Array(IP).fill(0);
let debugInfo = {};
// Initialize memory-mapped IO -- TODO this should probably be in the CPU, not here
machineCode[POINTER_TO_DISPLAY] = DISPLAY_ADDR;
// Initialize arrays that collect code references that
// have to be revisited after our first pass through the source
let labels = {};
let constants = {};
// Decode line by line...
for (let i = 0; i < lines.length; i++) {
let line = lines[i];
// dbg(2, `line info:`);
// dbg(2, line);
if (line.type === 'code') {
const op = line.operation;
if (typeof line.argument === 'undefined') {
// If this isn't a label definition,
// or one of the ops with optional arguments,
// then it's an error
if (!line.operation.startsWith('@')) {
if (mnemonicsWithOptionalArgs.indexOf(line.operation.toLowerCase()) < 0) {
console.error('');
console.error(`Error: Missing operand ${line.source}`);
console.error(` at line ${line.number}`);
process.exit();
} else {
// It *is* one of the special optional-arg ops
// So let's fill in the implicit operand with $00
line.argument = '0';
}
}
}
// *** Decode special operations ***
// Opcodes - Handle label definitions
if (op.startsWith(ASM_LABEL_PREFIX)) {
labels = handleLabelDefinition(op, IP, labels);
continue;
}
// Opcodes - Handle constant definitions
if (op.startsWith(ASM_CONSTANT_PREFIX)) {
constants = handleConstantDefinitions(op, line.argument, IP, constants);
continue;
}
// Opcodes - Handle setting value of IP
if (op.startsWith(ASM_IP_LABEL)) {
IP = parseInt(line.argument);
continue;
}
// *** Decode regular operations ***
/** @type {number|null} decodedOp **/
let decodedOp = null;
/** @type {number|null} decodedArg **/
let decodedArg = null;
/** @typedef {'direct'|'indirect'} AddressingMode **/
let addressingMode = 'direct';
// Now that it can't be a label or a constant, normalize the opcode
line.operation = line.operation.toLowerCase();
// Operands - Handle references to labels
if (line.argument.startsWith(ASM_LABEL_PREFIX)) {
let label = line.argument.substring(1); // strip label prefix
if (label in labels) {
dbg(1, `'${label}' already in labels object`);
labels[label].bytesToReplace.push(IP + 1);
} else {
dbg(1, `'${label}' NOT in labels object`);
labels[label] = {
bytesToReplace: [IP + 1],
};
}
dbg(1, `Label reference:`);
dbg(1, ` Points to byte: ${labels[label].pointsToByte}`);
dbg(1, ` Bytes to replace: ${labels[label].bytesToReplace}`);
decodedArg = 0; // Return 0 for operand for now -- we'll replace it later
}
// Operands - Handle references to the Instruction Pointer
if (line.argument === ASM_IP_LABEL) {
dbg(1, ` References current IP - ${IP}`);
if (typeof line.extraArgument === 'undefined') {
decodedArg = IP;
} else {
decodedArg = IP + decodeNumericOp(line.extraArgument);
}
}
// Operands - Handle references to constants
if (line.argument.startsWith(ASM_CONSTANT_PREFIX)) {
dbg(1, `References '${line.argument}'`);
if (typeof constants[line.argument.substring(1)] === 'undefined') {
console.error();
console.error(`Error: Undefined constant '${line.argument}'`);
console.error(` at line ${line.number}`);
process.exit();
}
decodedArg = decodeNumericOp(constants[line.argument.substring(1)]); // substring(1) strips '>'
}
// Operands - Handle references to constants in indirect mode
if (line.argument.startsWith(`(${ASM_CONSTANT_PREFIX}`)) {
addressingMode = "indirect";
dbg(1, `(Indirectly) References '${line.argument}'`);
let constName = line.argument.replace(`(${ASM_CONSTANT_PREFIX}`, "");
constName = constName.replace(")", "");
decodedArg = decodeNumericOp(constants[constName]);
}
// Operands - Handle indirect expressions
if (decodedArg === null && line.argument.startsWith("(")) {
addressingMode = "indirect";
let indyTemp = line.argument.replace("(", "").replace(")", "");
decodedArg = decodeNumericOp(indyTemp);
}
// Decode regular opcodes
if (decodedOp === null) {
decodedOp = mnemonics2opcodes[line.operation][addressingMode];
}
// Decode regular operands
if (decodedArg === null) {
decodedArg = decodeNumericOp(line.argument);
}
machineCode[IP] = decodedOp;
machineCode[IP + 1] = decodedArg;
debugInfo[IP] = {
lineNumber: line.number,
source: line.source,
address: IP,
machine: [decodedOp, decodedArg]
};
dbg(3, ``);
dbg(3, `Line ${line.number}: ${line.source}`);
if (line.argument) {
dbg(3, ` Asm operation: ${line.operation.toUpperCase()} ${line.argument}`);
} else if (line.operation) {
dbg(3, ` Asm operation: ${line.operation.toUpperCase()}`);
}
dbg(3, ` Machine code: $${num2hex(decodedOp)} $${num2hex(decodedArg)}`);
dbg(3, ` IP: $${num2hex(IP)}`);
IP += 2;
};
}
dbg(1, '');
dbgGroup(1, 'Memory before filling in label constants');
dbgExec(1, () => logMemory(new Uint8Array(machineCode)));
dbgGroupEnd(1);
// Backfill label references
for (let k of Object.keys(labels)) {
dbgGroup(1, `${ASM_LABEL_PREFIX}${k}`);
let label = labels[k];
dbg(1, `Points to byte: ${label.pointsToByte}`);
dbg(1, `Bytes to replace: ${label.bytesToReplace}`);
dbgGroupEnd(1);
for (let j = 0; j < label.bytesToReplace.length; j++) {
machineCode[label.bytesToReplace[j]] = label.pointsToByte;
}
}
return { 'debugInfo': debugInfo, 'machineCode': new Uint8Array(machineCode) };
}
/**
* @param {string} line
* @returns {string}
**/
function stripComments(line) {
return line.replace(/;.+/,"");
}
/**
* @param {string} line
* @returns {string}
**/
function stripWhitespaceFromEnds(line) {
line = line.replace(/^\s+/,"");
line = line.replace(/\s+$/,"");
return line;
}
function hex2num(hex) { return parseInt(hex, 16) };
// Debug helpers
const dbg = (lvl, s) => { if (DEBUG && (lvl >= DEBUG_LEVEL)) console.log(s) };
const dbgGroup = (lvl, s) => { if (DEBUG && (lvl >= DEBUG_LEVEL)) console.group(s) };
const dbgGroupEnd = (lvl, s) => { if (DEBUG && (lvl >= DEBUG_LEVEL)) console.groupEnd() };
const dbgExec = (lvl, func) => { if (DEBUG && (lvl >= DEBUG_LEVEL)) func(); }

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const readline = require('readline');
const readlineSync = require('readline-sync');
const {
INITIAL_IP_ADDRESS,
DEFAULT_CYCLE_LIMIT,
KEYPAD_ADDR,
KEY_MAP,
} = require('./machine.config');
const {
num2hex,
bool2bit,
} = require('./logging.js');
const display = require('./display.js');
// STATE
const CPU = {
// Core state
running: false,
IP: INITIAL_IP_ADDRESS,
FLAGS: {'C': false, 'Z': false, 'N': false, 'O': false},
FLAGNUMS2NAMES: {0: 'C', 1: 'Z', 2: 'N', 3: 'O'},
Acc: 0,
memory: null,
// Functions that update core state
/** @param {Uint8Array} data */
loadMemory: (data) => {
CPU.memory = new Uint8Array(256);
CPU.memory.set(data, 0);
},
incrementIP: (offset) => {
CPU.previousIP = CPU.IP;
CPU.IP = CPU.IP + offset;
},
setIP: (address) => {
CPU.previousIP = CPU.IP;
CPU.IP = address;
},
updateFlagZero: () => { CPU.FLAGS.Z = CPU.Acc === 0; },
updateFlagNegative: () => { CPU.Acc & 128 ? CPU.FLAGS.N = true : CPU.FLAGS.N = false },
// Debug info
previousIP: 0,
currentInstruction: {
opcode: null,
operand: null,
mnemonic: null,
},
cycleCounter: 0,
}
// FUNCTIONS THAT MODIFY STATE
const Instructions = {
end: () => {
CPU.currentInstruction.mnemonic = 'END';
CPU.running = false;
CPU.incrementIP(2);
},
store_lit: (lit) => {
CPU.currentInstruction.mnemonic = 'STO lit';
CPU.memory[lit] = CPU.Acc;
CPU.incrementIP(2);
},
store_addr: (addr) => {
CPU.currentInstruction.mnemonic = `STO addr; @addr: ${num2hex(CPU.memory[addr])}`;
CPU.memory[CPU.memory[addr]] = CPU.Acc;
CPU.incrementIP(2);
},
load_lit: (lit) => {
CPU.currentInstruction.mnemonic = 'LDA lit';
CPU.Acc = lit;
CPU.updateFlagNegative();
CPU.updateFlagZero();
CPU.incrementIP(2);
},
load_addr: (addr) => {
CPU.currentInstruction.mnemonic = `LDA addr; @ addr: ${num2hex(CPU.memory[addr])}`;
CPU.Acc = CPU.memory[addr];
CPU.updateFlagNegative();
CPU.updateFlagZero();
CPU.incrementIP(2);
},
add_lit: (lit) => {
CPU.currentInstruction.mnemonic = 'ADD lit';
// Calculate sum
let sum = CPU.Acc + lit;
if (sum > 255) {
CPU.FLAGS.C = true;
sum = (sum % 255) - 1;
} else {
CPU.FLAGS.C = false;
}
// Calculate overflow flag status
let bitSixCarry = 0;
if ((CPU.Acc & 64) && (lit & 64)) { bitSixCarry = 1; }
// let overflow = bitSixCarry ^ (CPU.FLAGS & 8);
// FIXME FIXME FIXME
// I'm on a plane and can't remember how this works
let overflow = 0;
if (overflow) {
CPU.FLAGS.O = true;
} else {
CPU.FLAGS.O = false;
}
CPU.Acc = sum;
CPU.updateFlagNegative();
CPU.updateFlagZero();
CPU.incrementIP(2);
},
add_addr: (addr) => {
CPU.currentInstruction.mnemonic = 'ADD addr';
// Calculate sum
let sum = CPU.Acc + CPU.memory[addr];
if (sum > 255) {
CPU.FLAGS.C = true;
sum = (sum % 255) - 1;
} else {
CPU.FLAGS.C = false;
}
// Calculate overflow flag status
let bitSixCarry = 0;
if ((CPU.Acc & 64) && (addr & 64)) { bitSixCarry = 1; }
// let overflow = bitSixCarry ^ (CPU.FLAGS & 8);
// FIXME FIXME FIXME
// I'm on a plane and can't remember how this works
let overflow = 0;
if (overflow) {
CPU.FLAGS.O = true;
} else {
CPU.FLAGS.O = false;
}
CPU.Acc = sum;
CPU.updateFlagNegative();
CPU.updateFlagZero();
CPU.incrementIP(2);
},
sub_lit: (lit) => {
CPU.currentInstruction.mnemonic = 'SUB lit';
// Calculate sum
let sum = CPU.Acc - lit;
if (sum < 0) {
CPU.FLAGS.C = true;
sum = sum + 256;
} else {
CPU.FLAGS.C = false;
}
// Calculate overflow flag status
let bitSixCarry = 0;
if ((CPU.Acc & 64) && (lit & 64)) { bitSixCarry = 1; }
// let overflow = bitSixCarry ^ (CPU.FLAGS & 8);
// FIXME FIXME FIXME
// I'm on a plane and can't remember how this works
let overflow = 0;
if (overflow) {
CPU.FLAGS.O = true;
} else {
CPU.FLAGS.O = false;
}
CPU.Acc = sum;
CPU.updateFlagNegative();
CPU.updateFlagZero();
CPU.incrementIP(2);
},
sub_addr: (addr) => {
CPU.currentInstruction.mnemonic = 'SUB addr';
// Calculate sum
let sum = CPU.Acc - CPU.memory[addr];
if (sum < 0) {
CPU.FLAGS.C = true;
sum = sum + 256;
} else {
CPU.FLAGS.C = false;
}
// Calculate overflow flag status
let bitSixCarry = 0;
if ((CPU.Acc & 64) && (addr & 64)) { bitSixCarry = 1; }
// let overflow = bitSixCarry ^ (CPU.FLAGS & 8);
// FIXME FIXME FIXME
// I'm on a plane and can't remember how this works
let overflow = 0;
if (overflow) {
CPU.FLAGS.O = true;
} else {
CPU.FLAGS.O = false;
}
CPU.Acc = sum;
CPU.updateFlagNegative();
CPU.updateFlagZero();
CPU.incrementIP(2);
},
hop_lit: (lit) => {
CPU.currentInstruction.mnemonic = `HOP lit; IP+2: ${CPU.memory[CPU.IP+2]}, IP+3: ${CPU.memory[CPU.IP+3]}`;
if (CPU.Acc === lit) {
CPU.incrementIP(4);
} else {
CPU.incrementIP(2);
}
},
hop_addr: (addr) => {
CPU.currentInstruction.mnemonic = 'HOP addr';
if (CPU.Acc === CPU.memory[addr]) {
CPU.incrementIP(4);
} else {
CPU.incrementIP(2);
}
},
jump_lit: (lit) => {
CPU.currentInstruction.mnemonic = 'JMP lit';
CPU.setIP(lit);
},
jump_addr: (addr) => {
CPU.currentInstruction.mnemonic = 'JMP addr';
CPU.setIP(CPU.memory[addr]);
},
flag_toggle: (flagNum) => {
if (flagNum === null) {
console.error('Invalid flag number');
process.exit();
}
const flagName = CPU.FLAGNUMS2NAMES[flagNum];
CPU.currentInstruction.mnemonic = `FTG ${flagName}`;
CPU.FLAGS[flagName] = !CPU.FLAGS[flagName];
CPU.incrementIP(2);
},
flag_hop: (flagNum) => {
if (flagNum === null) {
console.error('Invalid flag number');
process.exit();
}
const flagName = CPU.FLAGNUMS2NAMES[flagNum];
CPU.currentInstruction.mnemonic = `FHP ${flagName}; IP+2: ${CPU.memory[CPU.IP+2]}, IP+3: ${CPU.memory[CPU.IP+3]}`;
if (CPU.FLAGS[CPU.FLAGNUMS2NAMES[flagNum]]) {
CPU.incrementIP(4);
} else {
CPU.incrementIP(2);
}
},
no_op: () => {
CPU.currentInstruction.mnemonic = `NOP`;
CPU.incrementIP(2);
},
}
const opcodes2mnemonics = {
0: (operand) => Instructions.end(),
1: (operand) => Instructions.store_lit(operand),
2: (operand) => Instructions.store_addr(operand),
3: (operand) => Instructions.load_lit(operand),
4: (operand) => Instructions.load_addr(operand),
5: (operand) => Instructions.add_lit(operand),
6: (operand) => Instructions.add_addr(operand),
7: (operand) => Instructions.sub_lit(operand),
8: (operand) => Instructions.sub_addr(operand),
9: (operand) => Instructions.hop_lit(operand),
10: (operand) => Instructions.hop_addr(operand),
11: (operand) => Instructions.jump_lit(operand),
12: (operand) => Instructions.jump_addr(operand),
13: (operand) => Instructions.flag_toggle(operand),
14: (operand) => Instructions.flag_hop(operand),
15: (operand) => Instructions.no_op(),
};
/**
* Load code into memory and set CPU state to "running"
* @param {Uint8Array} code - Machine code to load
**/
function startCPU(code) {
CPU.loadMemory(code);
CPU.cycleCounter = 0;
CPU.running = true;
// FIXME: This conflicts with single-stepping
// (you can single-step, but keys aren't passed
// through to the Cardiograph)
//
// -> The fix is maybe to remove readlineSync,
// and instead stash the keypress into a buffer variable.*
// Then have the stepping function check that buffer,
// and then clear the buffer, each time it runs.
//
// * If it's in the set of keys that are relevant
// to single-stepping.
// Start listening for keypresses...
readline.emitKeypressEvents(process.stdin);
if (process.stdin.setRawMode != null) {
process.stdin.setRawMode(true);
}
process.stdin.on('keypress', (str, key) => { // TODO: is it possible to turn this off again?
if (key.sequence === '\x03') process.exit();
let name = key.name.toUpperCase();
if (name in KEY_MAP) {
CPU.memory[KEYPAD_ADDR] = KEY_MAP[name];
}
});
}
/**
* Execute just the next instruction in memory
* @param {Object} debugInfo
* @param {Boolean} [debug] - Print machine status and the line of code being executed
**/
async function stepCPU(debugInfo, debug = false, prettyPrintDisplay = false) {
if (CPU.IP >= CPU.memory.length) {
console.error('HALTING - IP greater than memory size');
CPU.running = false;
process.exit();
} else {
CPU.currentInstruction.opcode = CPU.memory[CPU.IP];
CPU.currentInstruction.operand = CPU.memory[CPU.IP+1];
let executeInstruction = opcodes2mnemonics[CPU.currentInstruction.opcode];
if (typeof executeInstruction === 'undefined') {
let info = debugInfo[CPU.previousIP];
console.error();
console.error(`Error: Invalid opcode`);
console.error(` Executing $${num2hex(info.machine[0])} $${num2hex(info.machine[1])}`);
console.error(` from line ${info.lineNumber}: ${info.source}`);
process.exit();
}
executeInstruction(CPU.currentInstruction.operand);
CPU.cycleCounter += 1;
}
logCPUState(debugInfo, debug, prettyPrintDisplay);
if (DEFAULT_CYCLE_LIMIT) { // Temporary limit as a lazy way to halt infinite loops
if (CPU.cycleCounter >= DEFAULT_CYCLE_LIMIT) {
console.warn(' HALTING - reached cycle limit');
CPU.running = false;
}
}
if (!CPU.running) process.exit();
}
/**
* @param {Uint8Array} code - Machine code to run
* @param {Object} debugInfo TODO type
* @param {Boolean} [debug] - Enable/disable debugging printouts
* @param {Boolean} [singleStep]
* @param {Boolean} [prettyPrint] - Print display with black and white emoji, instead of in hex
* @param {Number} [clockSpeed] - CPU clock speed in milliseconds
**/
exports.runProgram =
(code, debugInfo, debug=false, singleStep=false, prettyPrint=false, clockSpeed=100) => {
if (singleStep) {
this.singleStepProgram(code, debugInfo, debug, prettyPrint);
} else {
startCPU(code);
// Animate the output by pausing between steps
const loop = setInterval(async () => {
stepCPU(debugInfo, debug, prettyPrint);
if (!CPU.running) {
logCPUState(debugInfo, debug, prettyPrint);
console.log('Halted');
process.exit();
}
}, clockSpeed);
}
};
/**
* @param {Uint8Array} code - Machine code to run
* @param {any} debugInfo - TODO
* @param {Boolean} [debug] - Enable/disable debugging printouts
* @param {Boolean} [prettyPrintDisplay] - Print display using black and white emoji
**/
exports.singleStepProgram = (code, debugInfo, debug = false, prettyPrintDisplay = false) => {
startCPU(code);
while (CPU.running) {
stepCPU(debugInfo, debug, prettyPrintDisplay);
// FIXME: this prevents exiting with Ctrl+C:
let key = readlineSync.keyIn('S to step, Q to quit > ', {
limit: ['s', 'S', 'q', 'Q'],
});
if (key.toLowerCase() === 'q') { process.exit(); }
console.log();
}
}
// FUNCTIONS THAT PULL INFO FROM STATE TO DISPLAY
/**
* @param {Boolean} [debug] - Enable/disable debugging printouts
**/
function logCPUState(debugInfo, debug = false, prettyPrintDisplay = false) {
debugInfo = debugInfo[CPU.previousIP] !== 'undefined' ? debugInfo[CPU.previousIP] : false;
console.group(`Step ${CPU.cycleCounter}`);
console.log();
if (!debug) console.clear();
display.show(CPU.memory, prettyPrintDisplay);
console.log();
if (debugInfo) {
console.log(`Line ${debugInfo.lineNumber}: ${debugInfo.source}`);
console.log();
}
console.log('Mnemonic:', CPU.currentInstruction.mnemonic);
console.log(`Machine: $${num2hex(CPU.currentInstruction.opcode)} $${num2hex(CPU.currentInstruction.operand)}`);
console.log();
console.log(`IP: $${num2hex(CPU.IP)} Acc: $${num2hex(CPU.Acc)} ONZC ${bool2bit(CPU.FLAGS.O)}${bool2bit(CPU.FLAGS.N)}${bool2bit(CPU.FLAGS.Z)}${bool2bit(CPU.FLAGS.C)}`);
console.log(`KEY: $${num2hex(CPU.memory[KEYPAD_ADDR])}  ${CPU.running ? "running" : "halted" }`);
console.log();
console.log();
console.groupEnd();
};

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@ -1,22 +0,0 @@
const { POINTER_TO_DISPLAY } = require('./machine.config');
const { num2hex } = require('./logging.js');
/**
* Print the contents of display memory
* by default, each pixel is shown as a hex number
* @param {Uint8Array} mem - CPU memory
* @param {Boolean} pretty - Display pixels using black and white emoji circles
**/
const printDisplay = (mem, pretty=false) => {
const disp = mem[POINTER_TO_DISPLAY];
const num2pic = (n) => n > 0 ? '⚫' : '⚪';
let fmt = (n) => num2hex(n);
if (pretty) fmt = (n) => num2pic(n);
for (let i = disp; i < disp + 25; i += 5) {
console.log(`${fmt(mem[i])} ${fmt(mem[i+1])} ${fmt(mem[i+2])} ${fmt(mem[i+3])} ${fmt(mem[i+4])}`);
}
}
module.exports = {
"show": printDisplay,
}

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@ -1,6 +0,0 @@
{
"compilerOptions": {
"checkJs": true
},
"exclude": ["node_modules", "**/node_modules/*"]
}

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@ -1,91 +0,0 @@
/**
* Display a table of memory locations.
* Call with [start] and [end] indices to display a range.
* @param {Uint8Array} mem - Memory to display
* @param {number} [start] - A start-index, in decimal
* @param {number} [end] - An end-index, in decimal
**/
const logMemory = (mem, start=0, end=mem.length) => {
let top1 = `┌─────────┬────────┬─────────┐`;
let top2 = `│ addrs │ opcode │ operand │`;
let top3 = `├─────────┼────────┼─────────┤`;
let blnk = `│ │ │ │`;
let bot1 = `└─────────┴────────┴─────────┘`;
console.log(`${top1}\n${top2}\n${top3}`);
for (let i = start; i < mem.length; i +=2) {
let operand = mem[i+1];
if (typeof operand === 'undefined') {
console.log(` ${num2hex(i)} ${num2hex(i+1)}${num2hex(mem[i])} │ │`);
} else {
console.log(`${num2hex(i)} ${num2hex(i+1)}${num2hex(mem[i])}${num2hex(operand)}`);
}
// Add a blank row every 4 lines:
let rowNum = i - start + 2; // Not actually the row number...
if ((rowNum % 8 === 0)
&& (i < (mem.length - 2))) {
console.log(blnk);
}
}
console.log(bot1);
}
const logRunningHeader = () => {
console.log();
let time = new Date();
console.log( `┌─────────────────────┐`);
console.log( `│ Running at ${time.toLocaleTimeString('en-GB')}` );
console.log( `└─────────────────────┘`);
}
/**
* @param {number} num
* @returns {string}
*/
const num2hex = (num) => num.toString(16).toUpperCase().padStart(2, "0");
/**
* @param {string} hex
* @returns {number}
*/
const hex2num = (hex) => parseInt(hex, 16);
/**
* Convert a number to binary, padded to 8 bits
* See here for an explanation: https://stackoverflow.com/questions/9939760/how-do-i-convert-an-integer-to-binary-in-javascript
* @param {number} num
* @returns {string} binary representation of the input
**/
const num2bin = (num) => (num >>> 0).toString(2).padStart(8, "0");
/**
* Convert a number to binary, padded to 4 bits
* See here for an explanation: https://stackoverflow.com/questions/9939760/how-do-i-convert-an-integer-to-binary-in-javascript
* @param {number} num
* @returns {string} binary representation of the input
**/
const num2bin_4bit = (num) => (num >>> 0).toString(2).padStart(4, "0");
/**
* @param {string} bin
* @returns {number}
*/
const bin2num = (bin) => parseInt(bin, 2)
/**
* @param {Boolean} bool
* @returns {0|1}
**/
const bool2bit = (bool) => bool ? 1 : 0;
module.exports = {
"logMemory": logMemory,
"logRunningHeader": logRunningHeader,
"num2hex": num2hex,
"hex2num": hex2num,
"num2bin": num2bin,
"num2bin_4bit": num2bin_4bit,
"bin2num": bin2num,
"bool2bit": bool2bit,
}

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@ -1,31 +0,0 @@
module.exports = {
"INITIAL_IP_ADDRESS": 29,
// Use these in CPU:
"DISPLAY_ADDR": 0,
"KEYPAD_ADDR": 27,
// Store the `DISPLAY_ADDR` at this address when assembling:
"POINTER_TO_DISPLAY": 26,
"KEY_MAP": {
// Same layout as COSMAC VIP / CHIP-8
// (This object maps qwerty keys to hex keys
// so that they are arranged in the same layout
// as the real keypad)
'1':'1', '2':'2', '3':'3', '4':'C',
'Q':'4', 'W':'5', 'E':'6', 'R':'D',
'A':'7', 'S':'8', 'D':'9', 'F':'E',
'Z':'A', 'X':'0', 'C':'B', 'V':'F',
// Include conventional arrow keys
'UP': '5',
'LEFT': '7',
'DOWN': '8',
'RIGHT': '9',
},
// max number of times to step the CPU,
// to stop endless loops
// 0 = infinite
"DEFAULT_CYCLE_LIMIT": 2048,
}

1060
src/package-lock.json generated

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@ -1,13 +0,0 @@
{
"name": "paper-computer",
"scripts": {
"jsdoc": "./node_modules/.bin/jsdoc"
},
"devDependencies": {
"jsdoc": "^4.0.2",
"jsdoc-to-markdown": "^8.0.0"
},
"dependencies": {
"readline-sync": "^1.4.10"
}
}

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@ -1,33 +0,0 @@
#!/usr/bin/env node
// Run with hex output: `./run-assembler.js run assembly.asm`
// Run with binary output: `./run-assembler.js runbin assembly.asm`
// Debug: `./run-assembler.js debug assembly.asm`
const fs = require('fs');
const assembler = require('./assembler.js');
const { logMemory, num2hex, num2bin } = require('./logging.js');
const machineConfig = require('./machine.config.js');
const mode = process.argv[2];
const filename = process.argv[3];
const inputFile_str = fs.readFileSync(filename, 'utf8');
let assembler_output;
if (mode === "debug") {
assembler_output = assembler.assemble(inputFile_str, true);
console.log('');
console.group("Machine code output");
logMemory(assembler_output.machineCode, machineConfig.INITIAL_IP_ADDRESS);
console.groupEnd();
} else {
assembler_output = assembler.assemble(inputFile_str);
let output = '';
if (mode === 'runbin') { // print binary output
assembler_output.machineCode.forEach((n) => output = `${output} ${num2bin(n)}`);
} else { // print hex output
assembler_output.machineCode.forEach((n) => output = `${output} ${num2hex(n)}`);
}
console.log(output);
}

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@ -1,71 +0,0 @@
#!/usr/bin/env node
// Usage: ./run-cpu.js -f code.asm [--debug] [--step] [--pretty]
const fs = require('fs');
const computer = require('./cpu.js');
const assembler = require('./assembler.js');
const { logRunningHeader } = require('./logging.js');
// Load file...
let filename;
try {
filename = getArgumentValue('-f', `Missing filename`);
} catch (error) {
console.error(error.message);
process.exit()
}
const inputFile_str = fs.readFileSync(filename, 'utf8');
// Check optional arguments...
let debug = false;
let singleStep = false;
let prettyPrint = false;
process.argv.forEach((arg) => { if (arg === '--debug') { debug = true } });
process.argv.forEach((arg) => { if (arg === '--step') { singleStep = true } });
process.argv.forEach((arg) => { if (arg === '--pretty') { prettyPrint = true } });
let speed = null;
process.argv.forEach((arg, index) => {
if (arg === '--speed' && process.argv.length > (index -1)) {
speed = parseInt(process.argv[index + 1]);
}
});
let assemblerOutput = assembler.assemble(inputFile_str);
logRunningHeader();
computer.runProgram(
assemblerOutput.machineCode,
assemblerOutput.debugInfo,
debug,
singleStep,
prettyPrint,
speed
);
// CLI args TODO
// - check if value is the name of another arg
// - usage info
// - catch nonexistant flags
/**
* @param {string} flag - The command line flag, eg. '-f'
* @param {string} errorMessage - The error to throw if a value isn't found
* @returns {string}
**/
function getArgumentValue(flag, errorMessage) {
let value = null;
process.argv.forEach((arg, index) => {
if (arg === flag && process.argv.length > (index -1)) {
value = process.argv[index + 1];
}
});
if (!value) throw new Error(errorMessage);
return value;
}