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simulator.js
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simulator.js
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"use strict";
function simulateOneInstruction() {
try {
PC = PC %
4096; // If you are at the end of a program, and there is no "return"
// there, jump to the beginning of the program. I think that's
// how PicoBlaze behaves, though I haven't tried it.
if (breakpoints.includes(machineCode[PC].line)) {
alert("Reached breakpoint on the line #" + machineCode[PC].line + ".");
if (playing)
clearInterval(simulationThread);
playing = false;
document.getElementById("fastForwardButton").disabled = false;
document.getElementById("singleStepButton").disabled = false;
document.getElementById("UART_INPUT").disabled = false;
document.getElementById("playImage").style.display = "inline";
document.getElementById("pauseImage").style.display = "none";
}
if (!playing || document.getElementById("shouldWeUpdateRegisters").checked)
document.getElementById("PC_label_" + formatAsAddress(PC)).innerHTML = "";
const currentDirective = parseInt(machineCode[PC].hex, 16);
// "bennyboy" from "atheistforums.org" thinks my program can be
// speeded up by using a switch-case instead of the large if-else (that a
// switch-case would compile into a more efficient assembly code), so it
// would be interesting to investigate whether that's true:
// https://atheistforums.org/thread-61911-post-2112817.html#pid2112817
let port, firstRegister, secondRegister, firstValue, secondValue, result,
value, registerIndex, registerValue;
switch (currentDirective & 0xff000) {
// if ((currentDirective & 0xff000) === 0x00000) {
case 0x00000:
// LOAD register,register
registers[regbank][parseInt(machineCode[PC].hex[2], 16)] =
registers[regbank][parseInt(machineCode[PC].hex[3], 16)];
PC++;
// } else if ((currentDirective & 0xff000) === 0x01000) {
break;
case 0x01000:
// LOAD register,constant
registers[regbank][parseInt(machineCode[PC].hex[2], 16)] = parseInt(
machineCode[PC].hex.substring(3),
16); // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
PC++;
// } else if ((currentDirective & 0xff000) === 0x17000) {
break;
case 0x17000:
// STAR register,constant ;Storing a constant into an inactive register
registers[!regbank | 0 /*That is how you convert a boolean to an integer
in JavaScript.*/
][parseInt(machineCode[PC].hex[2], 16)] =
parseInt(
machineCode[PC].hex.substring(3),
16); // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
PC++;
// } else if ((currentDirective & 0xff000) === 0x16000) {
break;
case 0x16000:
// STAR register,register ;Copying from an active register into an
// inactive one.
registers[!regbank | 0][parseInt(machineCode[PC].hex[2], 16)] =
registers[regbank][parseInt(machineCode[PC].hex[3], 16)];
PC++;
// } else if ((currentDirective & 0xff000) === 0x2e000) {
break;
case 0x2e000:
// STORE register,(register) ;Store the first register at the memory
// location where the second register points to.
memory[registers[regbank][parseInt(machineCode[PC].hex[3], 16)]] =
registers[regbank][parseInt(machineCode[PC].hex[2], 16)];
document
.getElementById(
"memory_" +
formatAsByte(
registers[regbank][parseInt(machineCode[PC].hex[3], 16)]))
.innerHTML = formatAsByte(
registers[regbank][parseInt(machineCode[PC].hex[2], 16)]);
PC++;
// } else if ((currentDirective & 0xff000) === 0x2f000) {
break;
case 0x2f000:
// STORE register,memory_address ;Copy a register onto a memory address.
memory[parseInt(
machineCode[PC].hex.substring(3),
16)] = // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
registers[regbank][parseInt(machineCode[PC].hex[2], 16)];
document
.getElementById(
"memory_" +
machineCode[PC].hex.substring(
3)) // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
.innerHTML = formatAsByte(
registers[regbank][parseInt(machineCode[PC].hex[2], 16)]);
PC++;
// } else if ((currentDirective & 0xff000) === 0x0a000) {
break;
case 0x0a000:
// FETCH register,(register) ;Dereference the pointer in the second
// register.
registers[regbank][parseInt(machineCode[PC].hex[2], 16)] =
memory[registers[regbank][parseInt(machineCode[PC].hex[3], 16)]];
PC++;
// } else if ((currentDirective & 0xff000) === 0x0b000) {
break;
case 0x0b000:
// FETCH register,memory_address ;Copy the value at memory_address to the
// register.
registers[regbank][parseInt(machineCode[PC].hex[2], 16)] = memory[parseInt(
machineCode[PC].hex.substring(3),
16)]; // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
PC++;
// } else if ((currentDirective & 0xff000) === 0x08000) {
break;
case 0x08000:
// INPUT register,(register) ;Read a byte from a port specified by a
// register.
/*const*/ port = registers[regbank][parseInt(machineCode[PC].hex[3], 16)];
if ((port === 2 || port === 3) && is_UART_enabled) {
if (port === 3) {
registers[regbank][parseInt(machineCode[PC].hex[2], 16)] =
document.getElementById("UART_INPUT")
.value.charCodeAt(currentlyReadCharacterInUART);
currentlyReadCharacterInUART++;
} else
registers[regbank][parseInt(machineCode[PC].hex[2], 16)] =
currentlyReadCharacterInUART <
document.getElementById("UART_INPUT").value.length
? 0b00001000 /*U_RX_D*/
: 0;
} else
registers[regbank][parseInt(machineCode[PC].hex[2], 16)] = parseInt(
document
.getElementById("input_" +
formatAsByte(registers[regbank][parseInt(
machineCode[PC].hex[3], 16)]))
.value,
16);
PC++;
// } else if ((currentDirective & 0xff000) === 0x09000) {
break;
case 0x09000:
// INPUT register, port_number
/*const*/ port = parseInt(
machineCode[PC].hex.substring(3),
16); // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
if ((port === 2 || port === 3) && is_UART_enabled) {
if (port === 3) {
// UART_RX_PORT
registers[regbank][parseInt(machineCode[PC].hex[2], 16)] =
document.getElementById("UART_INPUT")
.value.charCodeAt(currentlyReadCharacterInUART);
currentlyReadCharacterInUART++;
} else if (port === 2)
// UART_STATUS_PORT
registers[regbank][parseInt(machineCode[PC].hex[2], 16)] =
currentlyReadCharacterInUART <
document.getElementById("UART_INPUT").value.length
? 0b00001000 /*U_RX_D*/
: 0;
else {
alert(
"Internal simulator error: The simulator got into a forbidden state!");
stopSimulation();
}
} else
registers[regbank][parseInt(machineCode[PC].hex[2], 16)] = parseInt(
document
.getElementById(
"input_" +
machineCode[PC].hex.substring(
3)) // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
.value,
16);
PC++;
// } else if ((currentDirective & 0xff000) === 0x2c000) {
break;
case 0x2c000:
// OUTPUT register,(register) ;Output the result of the first register to
// the port specified by the second register.
/*const*/ port = registers[regbank][parseInt(machineCode[PC].hex[3], 16)];
/*const*/ value =
registers[regbank][parseInt(machineCode[PC].hex[2], 16)];
if ((port === 3 || port === 4) && is_UART_enabled) {
if (port === 3)
// UART_TX_PORT
document.getElementById("UART_OUTPUT").innerText +=
String.fromCharCode(value);
else if (port === 4)
// UART_RESET_PORT
document.getElementById("UART_OUTPUT").innerText = "";
else {
alert(
"Internal simulator error: The simulator got into a forbidden state!");
stopSimulation();
}
} else
output[registers[regbank][parseInt(machineCode[PC].hex[3], 16)]] =
registers[regbank][parseInt(machineCode[PC].hex[2], 16)];
displayOutput();
PC++;
// } else if ((currentDirective & 0xff000) === 0x2d000) {
break;
case 0x2d000:
// OUTPUT register, port_number
/*const*/ port = parseInt(
machineCode[PC].hex.substring(3),
16); // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
/*const*/ value =
registers[regbank][parseInt(machineCode[PC].hex[2], 16)];
if ((port === 3 || port === 4) && is_UART_enabled) {
if (port === 3)
// UART_TX_PORT
document.getElementById("UART_OUTPUT").innerText +=
String.fromCharCode(value);
else if (port === 4)
// UART_RESET_PORT
document.getElementById("UART_OUTPUT").innerText = "";
else {
alert(
"Internal simulator error: The simulator got into a forbidden state!");
stopSimulation();
}
} else {
output[parseInt(
machineCode[PC].hex.substring(3),
16)] = // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
registers[regbank][parseInt(machineCode[PC].hex[2], 16)];
displayOutput();
}
PC++;
// } else if ((currentDirective & 0xff000) === 0x2b000) {
break;
case 0x2b000:
// OUTPUTK constant, port_number
/*const*/ value = parseInt(
machineCode[PC].hex.substring(2, 2 + 2),
16); // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
/*const*/ port = parseInt(machineCode[PC].hex[4], 16);
if ((port === 3 || port === 4) && is_UART_enabled) {
if (port === 3)
// UART_TX_PORT
document.getElementById("UART_OUTPUT").innerText +=
String.fromCharCode(value);
else if (port === 4)
// UART_RESET_PORT
document.getElementById("UART_OUTPUT").innerText = "";
else {
alert(
"Internal simulator error: The simulator got into a forbidden state!");
stopSimulation();
}
} else {
output[parseInt(machineCode[PC].hex[4], 16)] = parseInt(
machineCode[PC].hex.substring(2, 2),
16); // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
displayOutput();
}
PC++;
/* } else if (currentDirective === 0x37000) {
// REGBANK A
regbank = 0;
PC++;
} else if (currentDirective === 0x37001) {
// REGBANK B
regbank = 1;
PC++;
*/
break;
case 0x37000:
if ((currentDirective & 0x00ff0) !== 0 || (currentDirective & 0xf) > 1) {
alert(
'Sorry about that, the simulator currently does not support the instruction "' +
machineCode[PC].hex + '" (' + currentDirective + " & " + 0xff000 +
" = " + (currentDirective & 0xff000) + "), assembled from line #" +
machineCode[PC].line + ".");
stopSimulation();
}
if (currentDirective % 2 === 0)
regbank = 0;
else
regbank = 1;
PC++;
// } else if ((currentDirective & 0xff000) === 0x22000) {
break;
case 0x22000:
// JUMP label
PC = parseInt(
machineCode[PC].hex.substring(2),
16); // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
/* } else if ((currentDirective & 0xff0ff) == 0x14080) {
// HWBUILD register
flagC[regbank] =
1; // Have a better idea? We can't simulate all of what this
directive
// does, but we can simulate this part of it.
PC++;
*/ // Moved to bit-shifting operations...
// } else if ((currentDirective & 0xff000) === 0x10000) {
break;
case 0x10000:
// ADD register, register
/*const*/ firstRegister = parseInt(machineCode[PC].hex[2], 16);
/*const*/ secondRegister = parseInt(machineCode[PC].hex[3], 16);
/*const*/ firstValue = registers[regbank][firstRegister];
/*const*/ secondValue = registers[regbank][secondRegister];
if ((firstValue + secondValue) % 256 === 0)
flagZ[regbank] = 1;
else
flagZ[regbank] = 0;
if (firstValue + secondValue > 255)
flagC[regbank] = 1;
else
flagC[regbank] = 0;
registers[regbank][firstRegister] += secondValue;
PC++;
// } else if ((currentDirective & 0xff000) === 0x11000) {
break;
case 0x11000:
// ADD register, constant
/*const*/ firstRegister = parseInt(machineCode[PC].hex[2], 16);
/*const*/ firstValue = registers[regbank][firstRegister];
/*const*/ secondValue = parseInt(
machineCode[PC].hex.substring(3),
16); // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
if ((firstValue + secondValue) % 256 === 0)
flagZ[regbank] = 1;
else
flagZ[regbank] = 0;
if (firstValue + secondValue > 255)
flagC[regbank] = 1;
else
flagC[regbank] = 0;
registers[regbank][firstRegister] += secondValue;
PC++;
// } else if ((currentDirective & 0xff000) === 0x12000) {
break;
case 0x12000:
// ADDCY register, register
/*const*/ firstRegister = parseInt(machineCode[PC].hex[2], 16);
/*const*/ secondRegister = parseInt(machineCode[PC].hex[3], 16);
/*const*/ firstValue = registers[regbank][firstRegister];
/*const*/ secondValue = registers[regbank][secondRegister];
/*const*/ result = firstValue + secondValue + flagC[regbank];
if (result % 256 === 0)
flagZ[regbank] = 1;
else
flagZ[regbank] = 0;
if (result > 255)
flagC[regbank] = 1;
else
flagC[regbank] = 0;
registers[regbank][firstRegister] = result;
PC++;
// } else if ((currentDirective & 0xff000) === 0x13000) {
break;
case 0x13000:
// ADDCY register, constant
/*const*/ firstRegister = parseInt(machineCode[PC].hex[2], 16);
/*const*/ firstValue = registers[regbank][firstRegister];
/*const*/ secondValue = parseInt(
machineCode[PC].hex.substring(3),
16); // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
/*const*/ result = firstValue + secondValue + flagC[regbank];
if (result % 256 === 0)
flagZ[regbank] = 1;
else
flagZ[regbank] = 0;
if (result > 255)
flagC[regbank] = 1;
else
flagC[regbank] = 0;
registers[regbank][firstRegister] = result;
PC++;
// } else if ((currentDirective & 0xff000) === 0x18000) {
break;
case 0x18000:
// SUB register, register
/*const*/ firstRegister = parseInt(machineCode[PC].hex[2], 16);
/*const*/ secondRegister = parseInt(machineCode[PC].hex[3], 16);
/*const*/ firstValue = registers[regbank][firstRegister];
/*const*/ secondValue = registers[regbank][secondRegister];
/*const*/ result = firstValue - secondValue;
if (result % 256 === 0)
flagZ[regbank] = 1;
else
flagZ[regbank] = 0;
if (result < 0)
flagC[regbank] = 1;
else
flagC[regbank] = 0;
registers[regbank][firstRegister] = result;
PC++;
// } else if ((currentDirective & 0xff000) === 0x19000) {
break;
case 0x19000:
// SUB register, constant
/*const*/ firstRegister = parseInt(machineCode[PC].hex[2], 16);
/*const*/ firstValue = registers[regbank][firstRegister];
/*const*/ secondValue = parseInt(
machineCode[PC].hex.substring(3),
16); // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
/*const*/ result = firstValue - secondValue;
if (result % 256 === 0)
flagZ[regbank] = 1;
else
flagZ[regbank] = 0;
if (result < 0)
flagC[regbank] = 1;
else
flagC[regbank] = 0;
registers[regbank][firstRegister] = result;
PC++;
// } else if ((currentDirective & 0xff000) === 0x1a000) {
break;
case 0x1a000:
// SUBCY register, register
/*const*/ firstRegister = parseInt(machineCode[PC].hex[2], 16);
/*const*/ secondRegister = parseInt(machineCode[PC].hex[3], 16);
/*const*/ firstValue = registers[regbank][firstRegister];
/*const*/ secondValue = registers[regbank][secondRegister];
/*const*/ result = firstValue - secondValue - flagC[regbank];
if (result % 256 === 0)
flagZ[regbank] = 1;
else
flagZ[regbank] = 0;
if (result < 0)
flagC[regbank] = 1;
else
flagC[regbank] = 0;
registers[regbank][firstRegister] = result;
PC++;
// } else if ((currentDirective & 0xff000) === 0x1b000) {
break;
case 0x1b000:
// SUBCY register, constant
/*const*/ firstRegister = parseInt(machineCode[PC].hex[2], 16);
/*const*/ firstValue = registers[regbank][firstRegister];
/*const*/ secondValue = parseInt(
machineCode[PC].hex.substring(3),
16); // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
/*const*/ result = firstValue - secondValue - flagC[regbank];
if (result % 256 === 0)
flagZ[regbank] = 1;
else
flagZ[regbank] = 0;
if (result < 0)
flagC[regbank] = 1;
else
flagC[regbank] = 0;
registers[regbank][firstRegister] = result;
PC++;
// } else if ((currentDirective & 0xff000) === 0x03000) {
break;
case 0x03000:
// AND register, constant
/*const*/ firstRegister = parseInt(machineCode[PC].hex[2], 16);
/*const*/ firstValue = registers[regbank][firstRegister];
/*const*/ secondValue = parseInt(
machineCode[PC].hex.substring(3),
16); // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
/*const*/ result = firstValue & secondValue;
if (result % 256 === 0)
flagZ[regbank] = 1;
else
flagZ[regbank] = 0;
if (result % 256 === 255)
flagC[regbank] = 1;
else
flagC[regbank] = 0;
registers[regbank][firstRegister] = result;
PC++;
// } else if ((currentDirective & 0xff000) === 0x02000) {
break;
case 0x02000:
// AND register, register
/*const*/ firstRegister = parseInt(machineCode[PC].hex[2], 16);
/*const*/ secondRegister = parseInt(machineCode[PC].hex[3], 16);
/*const*/ firstValue = registers[regbank][firstRegister];
/*const*/ secondValue = registers[regbank][secondRegister];
/*const*/ result = firstValue & secondValue;
if (result % 256 === 0)
flagZ[regbank] = 1;
else
flagZ[regbank] = 0;
if (result % 256 === 255)
flagC[regbank] = 1;
else
flagC[regbank] = 0;
registers[regbank][firstRegister] = result;
PC++;
// } else if ((currentDirective & 0xff000) === 0x04000) {
break;
case 0x04000:
// OR register, register
/*const*/ firstRegister = parseInt(machineCode[PC].hex[2], 16);
/*const*/ secondRegister = parseInt(machineCode[PC].hex[3], 16);
/*const*/ firstValue = registers[regbank][firstRegister];
/*const*/ secondValue = registers[regbank][secondRegister];
/*const*/ result = firstValue | secondValue;
if (result % 256 === 0)
flagZ[regbank] = 1;
else
flagZ[regbank] = 0;
if (result % 256 === 255)
flagC[regbank] = 1;
else
flagC[regbank] = 0;
registers[regbank][firstRegister] = result;
PC++;
// } else if ((currentDirective & 0xff000) === 0x05000) {
break;
case 0x05000:
// OR register, constant
/*const*/ firstRegister = parseInt(machineCode[PC].hex[2], 16);
/*const*/ firstValue = registers[regbank][firstRegister];
/*const*/ secondValue = parseInt(
machineCode[PC].hex.substring(3),
16); // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
/*const*/ result = firstValue | secondValue;
if (result % 256 === 0)
flagZ[regbank] = 1;
else
flagZ[regbank] = 0;
if (result % 256 === 255)
flagC[regbank] = 1;
else
flagC[regbank] = 0;
registers[regbank][firstRegister] = result;
PC++;
// } else if ((currentDirective & 0xff000) === 0x06000) {
break;
case 0x06000:
// XOR register, register
/*const*/ firstRegister = parseInt(machineCode[PC].hex[2], 16);
/*const*/ secondRegister = parseInt(machineCode[PC].hex[3], 16);
/*const*/ firstValue = registers[regbank][firstRegister];
/*const*/ secondValue = registers[regbank][secondRegister];
/*const*/ result = firstValue ^ secondValue;
if (result % 256 === 0)
flagZ[regbank] = 1;
else
flagZ[regbank] = 0;
if (result % 256 === 255)
flagC[regbank] = 1;
else
flagC[regbank] = 0;
registers[regbank][firstRegister] = result;
PC++;
// } else if ((currentDirective & 0xff000) === 0x07000) {
break;
case 0x07000:
// XOR register, constant
/*const*/ firstRegister = parseInt(machineCode[PC].hex[2], 16);
/*const*/ firstValue = registers[regbank][firstRegister];
/*const*/ secondValue = parseInt(
machineCode[PC].hex.substring(3),
16); // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
/*const*/ result = firstValue ^ secondValue;
if (result % 256 === 0)
flagZ[regbank] = 1;
else
flagZ[regbank] = 0;
if (result % 256 === 255)
flagC[regbank] = 1;
else
flagC[regbank] = 0;
registers[regbank][firstRegister] = result;
PC++;
/* } else if ((currentDirective & 0xff000) === 0x0c000 ||
(currentDirective & 0xff000) === 0x0e000) {
*/
break;
case 0x0c000:
case 0x0e000:
// TEST register, register ;The same as "AND", but does not store the
// result (only the flags). I am not sure if there is a difference between
// "0c" and "0e", they appear to be the same.
/*const*/ firstRegister = parseInt(machineCode[PC].hex[2], 16);
/*const*/ secondRegister = parseInt(machineCode[PC].hex[3], 16);
/*const*/ firstValue = registers[regbank][firstRegister];
/*const*/ secondValue = registers[regbank][secondRegister];
/*const*/ result = firstValue & secondValue;
if (result % 256 === 0)
flagZ[regbank] = 1;
else
flagZ[regbank] = 0;
if (result % 256 === 255)
flagC[regbank] = 1;
else
flagC[regbank] = 0;
// registers[regbank][firstRegister] = result;
PC++;
/* } else if ((currentDirective & 0xff000) === 0x0d000 ||
(currentDirective & 0xff000) === 0x0f000) {*/
break;
case 0x0d000:
case 0x0f000:
// TEST register, constant
/*const*/ firstRegister = parseInt(machineCode[PC].hex[2], 16);
/*const*/ firstValue = registers[regbank][firstRegister];
/*const*/ secondValue = parseInt(
machineCode[PC].hex.substring(3),
16); // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
/*const*/ result = firstValue & secondValue;
if (result % 256 === 0)
flagZ[regbank] = 1;
else
flagZ[regbank] = 0;
if (result % 256 === 255)
flagC[regbank] = 1;
else
flagC[regbank] = 0;
// registers[regbank][firstRegister] = result;
PC++;
// } else if ((currentDirective & 0xff000) === 0x1c000) {
break;
case 0x1c000:
// COMPARE register, register
/*const*/ firstRegister = parseInt(machineCode[PC].hex[2], 16);
/*const*/ secondRegister = parseInt(machineCode[PC].hex[3], 16);
/*const*/ firstValue = registers[regbank][firstRegister];
/*const*/ secondValue = registers[regbank][secondRegister];
/*const*/ result = firstValue - secondValue;
if (result % 256 === 0)
flagZ[regbank] = 1;
else
flagZ[regbank] = 0;
if (result < 0)
flagC[regbank] = 1;
else
flagC[regbank] = 0;
// registers[regbank][firstRegister] = result;
PC++;
// } else if ((currentDirective & 0xff000) === 0x1d000) {
break;
case 0x1d000:
// COMPARE register, constant
/*const*/ firstRegister = parseInt(machineCode[PC].hex[2], 16);
/*const*/ firstValue = registers[regbank][firstRegister];
/*const*/ secondValue = parseInt(
machineCode[PC].hex.substring(3),
16); // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
/*const*/ result = firstValue - secondValue;
if (result % 256 === 0)
flagZ[regbank] = 1;
else
flagZ[regbank] = 0;
if (result < 0)
flagC[regbank] = 1;
else
flagC[regbank] = 0;
// registers[regbank][firstRegister] = result;
PC++;
// } else if ((currentDirective & 0xff000) === 0x1e000) {
break;
case 0x1e000:
// COMPARECY register, register
/*const*/ firstRegister = parseInt(machineCode[PC].hex[2], 16);
/*const*/ secondRegister = parseInt(machineCode[PC].hex[3], 16);
/*const*/ firstValue = registers[regbank][firstRegister];
/*const*/ secondValue = registers[regbank][secondRegister];
/*const*/ result = firstValue - secondValue - flagC[regbank];
if (result % 256 === 0)
flagZ[regbank] = 1;
else
flagZ[regbank] = 0;
if (result < 0)
flagC[regbank] = 1;
else
flagC[regbank] = 0;
// registers[regbank][firstRegister] = result;
PC++;
// } else if ((currentDirective & 0xff000) === 0x1f000) {
break;
case 0x1f000:
// COMPARECY register, constant
/*const*/ firstRegister = parseInt(machineCode[PC].hex[2], 16);
/*const*/ firstValue = registers[regbank][firstRegister];
/*const*/ secondValue = parseInt(
machineCode[PC].hex.substring(3),
16); // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
/*const*/ result = firstValue - secondValue - flagC[regbank];
if (result % 256 === 0)
flagZ[regbank] = 1;
else
flagZ[regbank] = 0;
if (result < 0)
flagC[regbank] = 1;
else
flagC[regbank] = 0;
// registers[regbank][firstRegister] = result;
PC++;
// } else if ((currentDirective & 0xff000) === 0x14000) {
break;
case 0x14000:
// Bit-shifting operations...
/*const*/ registerIndex = parseInt(machineCode[PC].hex[2], 16);
/*let*/ registerValue = registers[regbank][registerIndex];
console.log("DEBUG: Shifting the bits in register s" +
registerIndex.toString(16));
const set_flags_after_shift_left = () => {
flagC[regbank] = (registerValue > 255) | 0;
flagZ[regbank] = (registerValue % 256 === 0) | 0;
};
const set_flags_before_shift_right = () => {
flagC[regbank] = registerValue % 2;
flagZ[regbank] = (Math.floor(registerValue / 2) === 0) | 0;
};
switch (machineCode[PC].hex.substring(
3)) { // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
case "06": // SL0
registerValue <<= 1;
set_flags_after_shift_left();
break;
case "07": // SL1
registerValue = (registerValue << 1) + 1;
set_flags_after_shift_left();
break;
case "04": // SLX
registerValue = (registerValue << 1) + (registerValue % 2);
set_flags_after_shift_left();
break;
case "00": // SLA
registerValue = (registerValue << 1) + flagC[regbank];
set_flags_after_shift_left();
break;
case "02": // RL
registerValue = (registerValue << 1) + Math.floor(registerValue / 128);
set_flags_after_shift_left();
break;
case "0e": // SR0
set_flags_before_shift_right();
registerValue >>= 1;
break;
case "0f": // SR1
set_flags_before_shift_right();
registerValue = (registerValue >> 1) + 128;
break;
case "0a": // SRX
set_flags_before_shift_right();
registerValue =
(registerValue >> 1) + Math.floor(registerValue / 128) * 128;
break;
case "08": // SRA
const oldFlagC = flagC[regbank];
set_flags_before_shift_right();
registerValue =
(registerValue >> 1) |
(oldFlagC
<< 7); // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/9
break;
case "0c": // RR
set_flags_before_shift_right();
registerValue = (registerValue >> 1) + 128 * (registerValue % 2);
break;
case "80": // HWBUILD (not a bit-shifting operation)
flagC[regbank] = 1;
break;
default:
alert('The instruction "' + machineCode[PC].hex +
'", assembled from line #' + machineCode[PC].line +
", hasn't been implemented yet, sorry about that!");
}
registers[regbank][registerIndex] = registerValue;
PC++;
// } else if ((currentDirective & 0xff000) === 0x32000) {
break;
case 0x32000:
// JUMP Z, label
if (flagZ[regbank])
PC = parseInt(
machineCode[PC].hex.substring(2),
16); // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
else
PC++;
// } else if ((currentDirective & 0xff000) === 0x36000) {
break;
case 0x36000:
// JUMP NZ, label
if (!flagZ[regbank])
PC = parseInt(
machineCode[PC].hex.substring(2),
16); // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
else
PC++;
// } else if ((currentDirective & 0xff000) === 0x3a000) {
break;
case 0x3a000:
// JUMP C, label
if (flagC[regbank])
PC = parseInt(
machineCode[PC].hex.substring(2),
16); // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
else
PC++;
// } else if ((currentDirective & 0xff000) === 0x3e000) {
break;
case 0x3e000:
// JUMP NC, label
if (!flagC[regbank])
PC = parseInt(
machineCode[PC].hex.substring(2),
16); // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
else
PC++;
// } else if ((currentDirective & 0xff000) === 0x26000) {
break;
case 0x26000:
// JUMP@ (register, register) ; Jump to the address pointed by the
// registers (something like function pointers, except that "return" won't
// work).
/*const*/ firstRegister = parseInt(machineCode[PC].hex[2], 16);
/*const*/ secondRegister = parseInt(machineCode[PC].hex[3], 16);
/*const*/ firstValue = registers[regbank][firstRegister];
/*const*/ secondValue = registers[regbank][secondRegister];
PC = (firstValue % 16) * 256 + secondValue;
// } else if ((currentDirective & 0xff000) === 0x20000) {
break;
case 0x20000:
// CALL functionName
callStack.push(PC);
PC = parseInt(
machineCode[PC].hex.substring(2),
16); // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
// } else if ((currentDirective & 0xff000) === 0x30000) {
break;
case 0x30000:
// CALL Z, functionName ; Call the function only if the Zero Flag is set.
if (flagZ[regbank]) {
callStack.push(PC);
PC = parseInt(
machineCode[PC].hex.substring(2),
16); // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
} else
PC++;
// } else if ((currentDirective & 0xff000) === 0x34000) {
break;
case 0x34000:
// CALL NZ, functionName ; Call the function only if the Zero Flag is not
// set.
if (!flagZ[regbank]) {
callStack.push(PC);
PC = parseInt(
machineCode[PC].hex.substring(2),
16); // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
} else
PC++;
// } else if ((currentDirective & 0xff000) === 0x38000) {
break;
case 0x38000:
// CALL C, functionName ; Call the function only if the Carry Flag is set.
if (flagC[regbank]) {
callStack.push(PC);
PC = parseInt(
machineCode[PC].hex.substring(2),
16); // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
} else
PC++;
// } else if ((currentDirective & 0xff000) === 0x3c000) {
break;
case 0x3c000:
// CALL NC, functionName ; Call the function only if the Carry Flag is not
// set.
if (!flagC[regbank]) {
callStack.push(PC);
PC = parseInt(
machineCode[PC].hex.substring(2),
16); // https://github.com/FlatAssembler/PicoBlaze_Simulator_in_JS/issues/30
} else
PC++;
// } else if ((currentDirective & 0xff000) === 0x24000) {
break;
case 0x24000:
// CALL@ (register, register) ; Jump the function pointed by the function
// pointer stored in the registers.
/*const*/ firstRegister = parseInt(machineCode[PC].hex[2], 16);
/*const*/ secondRegister = parseInt(machineCode[PC].hex[3], 16);
/*const*/ firstValue = registers[regbank][firstRegister];
/*const*/ secondValue = registers[regbank][secondRegister];
callStack.push(PC);
PC = (firstValue % 16) * 256 + secondValue;
// } else if ((currentDirective & 0xff000) === 0x25000) {
break;
case 0x25000:
// RETURN
if (callStack.length)
PC = callStack.pop() + 1;
else {
if (playing)
clearInterval(simulationThread);
alert("The program exited!");
}
// } else if ((currentDirective & 0xff000) === 0x31000) {
break;
case 0x31000:
// RETURN Z ; Return from a function only if the Zero Flag is set.
if (flagZ[regbank]) {
if (callStack.length)
PC = callStack.pop() + 1;
else {
if (playing)
clearInterval(simulationThread);
alert("The program exited!");
}
} else
PC++;
// } else if ((currentDirective & 0xff000) === 0x35000) {
break;
case 0x35000:
// RETURN NZ ; Return from a function only if the Zero Flag is not set.
if (!flagZ[regbank]) {
if (callStack.length)
PC = callStack.pop() + 1;
else {
if (playing)
clearInterval(simulationThread);
alert("The program exited!");
}
} else
PC++;
// } else if ((currentDirective & 0xff000) === 0x39000) {
break;
case 0x39000:
// RETURN C ; Return from a function only if the Carry Flag is set.
if (flagC[regbank]) {
if (callStack.length)
PC = callStack.pop() + 1;
else {
if (playing)
clearInterval(simulationThread);
alert("The program exited!");
}
} else
PC++;
// } else if ((currentDirective & 0xff000) === 0x3d000) {
break;
case 0x3d000:
// RETURN NC ; Return from a function only if the Carry Flag is not set.
if (!flagC[regbank]) {
if (callStack.length)
PC = callStack.pop() + 1;
else {
if (playing)
clearInterval(simulationThread);
alert("The program exited!");
}
} else
PC++;
// } else if ((currentDirective & 0xff000) === 0x28000) {
break;
case 0x28000:
// INTERRUPT ENABLE|DISABLE
flagIE = machineCode[PC].hex[4] | 0;
PC++;
// } else if ((currentDirective & 0xff000) === 0x29000) {
break;
case 0x29000:
// RETURNI ENABLE|DISABLE
flagIE = machineCode[PC].hex[4] | 0;
if (callStack.length)
PC = callStack.pop() + 1;
else {
if (playing)
clearInterval(simulationThread);
alert("The program exited!");
}
// } else {
break;
default:
alert(
'Sorry about that, the simulator currently does not support the instruction "' +
machineCode[PC].hex + '" (' + currentDirective + " & " + 0xff000 +
" = " + (currentDirective & 0xff000) + "), assembled from line #" +
machineCode[PC].line + ".");
stopSimulation();
}
displayRegistersAndFlags();
if (!playing || document.getElementById("shouldWeUpdateRegisters").checked)
document.getElementById("PC_label_" + formatAsAddress(PC)).innerHTML =
"<img src=\"https://icons.getbootstrap.com/assets/icons/arrow-right.svg\" alt=\"->\">";
} catch (error) {
if (playing)
clearInterval(simulationThread);
alert("The simulator crashed! Error: " + error.message);
}
}