This is a reimplementation of Multiple Modules (JS) where the filter computation is done in WASM.
const canvas = document.getElementById('canvas');
const hex_output = document.getElementById('hex');
const width = 128;
const height = 128;
canvas.width = width;
canvas.height = height;
canvas.style.border = '1px solid black';
const ctx = canvas.getContext('2d');
const avatar = new Image();
avatar.src = 'avatar.png';
await avatar.decode();
ctx.drawImage(avatar, 0, 0, 0x80, 0x80);
let imageData = ctx.getImageData(0, 0, width, height);
let x = 0;
let y = 0;
let offset = 0;
const mem = new WebAssembly.Memory({ initial: 1, maximum: 1 });
let heap = new Uint8ClampedArray(mem.buffer);
for (let index = 0; index < 0x100000; index++) {
heap[index] = imageData.data[index];
};
const check_boundary = () => {
if (x < 0) { x = 0 }
if (x > width - 1) { x = 0 }
if (y < 0) { y = 0 }
if (y > height - 1) { y = 0 }
offset = 4 * (y * width + x);
}
const move = (e) => {
e.preventDefault();
const rect = canvas.getBoundingClientRect();
const { changedTouches } = e;
if (changedTouches && changedTouches[0]) {
x = Math.floor(changedTouches[0].pageX - canvas.offsetLeft);
y = Math.floor(changedTouches[0].pageY - canvas.offsetTop);
}
else {
x = Math.floor(e.clientX - rect.left);
y = Math.floor(e.clientY - rect.top);
}
check_boundary();
hexdump();
};
canvas.addEventListener('mousemove', move, false);
canvas.addEventListener('touchmove', move, false);
const hexdump = () => {
const { data } = imageData;
let output = '';
for (let i = offset; i < offset + 0x100; i += 4) {
if (i < data.length - 4) {
for (let j = 3; j > -1; j--) {
if (data[i + j] < 0x10) {
output += `0${data[i + j].toString(16)}`;
} else {
output += `${data[i + j].toString(16)}`;
}
}
if (((i - offset) % 0x20) === 0x1c) {
output += '\n';
}
else {
output += ' ';
}
}
}
hex_output.innerHTML = `
x: 0x${parseInt(x).toString(16)}
y: 0x${parseInt(y).toString(16)}
offset: 0x${offset.toString(16)}
(mouse point = upper left corner of hexdump)
(8 x 8) i32 = 256 bytes (1/256 of the total memory of a 64K page)
(0x${0x10000.toString(16)} = 0x${0x100.toString(16)} * 0x${0x100.toString(16)} = ${0x100 * 0x100} )
${output}
`;
};
const canvas_render = () => {
for (let i = 0; i < imageData.data.length; i++) {
imageData.data[i] = heap[i];
}
ctx.putImageData(imageData, 0, 0);
}
const magic = [0x00, 0x61, 0x73, 0x6d];
const version = [0x01, 0x00, 0x00, 0x00];
const main = {
section_01: [
0x01, // type section
0x15, // 21 bytes
0x04, // number of functions
0x60, // import alpha filter
0x01, // takes 1 param ()
0x7f, // param i32
0x01,
0x7f, // result i32
0x60, // import grayscale filter
0x01, // takes 1 param ()
0x7f, // param i32
0x01,
0x7f, // result i32
0x60, // export alpha
0x02, // takes two params (range)
0x7f, // param i32
0x7f, // param i32
0x00, // no output
0x60, // export grayscale
0x02, // takes two params (range)
0x7f, // param i32
0x7f, // param i32
0x00, // no output
],
section_02: [
0x02, // import section
0x20, // 32 bytes
0x03, // 3 imports
0x01, // 1 byte
0x6a, // j
0x01, // 1 byte
0x6d, // m
0x02, // mem import
0x00, // min pages
0x01, // max pages
0x01, // 1 byte
0x6a, // j
0x05, // 5 byte name
0x61, // a
0x6c, // l
0x70, // p
0x68, // h
0x61, // a
0x00, // func
0x00, // alpha filter
0x01, // 1 byte
0x6a, // j
0x09, // 9 byte name
0x67, // g
0x72, // r
0x61, // a
0x79, // y
0x73, // s
0x63, // c
0x61, // a
0x6c, // l
0x65, // e
0x00, // func
0x01, // grayscale filter
],
section_03: [
0x03, // func section
0x03, // 2 bytes
0x02, // number of functions
0x02, // alpha
0x03, // grayscale
],
section_07: [
0x07, // export section
0x15, // 21 bytes
0x02, // number of exports
0x05, // 5 byte name
0x61, // a
0x6c, // l
0x70, // p
0x68, // h
0x61, // a
0x00, // function
0x02, // alpha
0x09, // 9 byte name
0x67, // g
0x72, // r
0x61, // a
0x79, // y
0x73, // s
0x63, // c
0x61, // a
0x6c, // l
0x65, // e
0x00, // function
0x03 // grayscale
],
section_0a: [
0x0a, // code section
0x45, // 69 bytes
0x02, // 2 function body
0x21, // 33 bytes
0x00, // no more local
0x03, // loop
0x40, // block
0x20, 0x00, // get address
0x20, 0x00, // get address
0x28, 0x02, 0x00, // i32.load the value
0x10, 0x00, // call alpha
0x36, 0x02, 0x00, // store
0x20, 0x00, // get address
0x20, 0x01, // upper limit
0x4b, // i32.gt_u compare
0x0d, 0x01, // br_if
0x20, 0x00, // get address
0x41, 0x04, // i32.const = 4
0x6a, // i32.add
0x21, 0x00, // set new address
0x0c, 0x00, // br 0
0x0b, // end block
0x0b, // end code
0x21, // 33 bytes
0x00, // no more local
0x03, // loop
0x40, // block
0x20, 0x00, // get address
0x20, 0x00, // get address
0x28, 0x02, 0x00, // i32.load the value
0x10, 0x01, // call grayscale
0x36, 0x02, 0x00, // store
0x20, 0x00, // get address
0x20, 0x01, // upper limit
0x4b, // i32.gt_u compare
0x0d, 0x01, // br_if
0x20, 0x00, // get address
0x41, 0x04, // i32.const = 4
0x6a, // i32.add
0x21, 0x00, // set new address
0x0c, 0x00, // br 0
0x0b, // end block
0x0b // end code
]
};
main.wasm = new Uint8Array(
magic.concat(version)
.concat(main.section_01)
.concat(main.section_02)
.concat(main.section_03)
.concat(main.section_07)
.concat(main.section_0a)
);
const alpha_filter = {
section_01: [
0x01, // type section
0x06, // 6 bytes
0x01, // number of functions
0x60, // filter
0x01, // takes 1 param ()
0x7f, // param i32
0x01,
0x7f // result i32
],
section_03: [
0x03, // func section
0x02, // 2 bytes
0x01, // number of functions
0x00 // filter
],
section_07: [
0x07, // export section
0x0a, // 10 bytes
0x01, // number of exports
0x06, // 6 byte name
0x66, // f
0x69, // i
0x6c, // l
0x74, // t
0x65, // e
0x72, // r
0x00, // function
0x00 // filter
],
section_0a: [
0x0a, // code section
0x0e, // 14 bytes
0x01, // number of function
0x0c, // 12 bytes filter
0x00, //
0x20, 0x00, // get the value
0x41, 0x80, 0x80, 0x80, 0xf8, 0x07, // i32.const 0x7f000000
0x6b, // 0xff****** - 0x7f****** = 0x80******
0x01,
0x0b // opcode for end
]
};
alpha_filter.wasm = new Uint8Array(
magic.concat(version)
.concat(alpha_filter.section_01)
.concat(alpha_filter.section_03)
.concat(alpha_filter.section_07)
.concat(alpha_filter.section_0a)
);
const grayscale_filter = {
section_01: [
0x01, // type section
0x06, // 6 bytes
0x01, // number of functions
0x60, // filter
0x01, // takes 1 param ()
0x7f, // param i32
0x01,
0x7f // result i32
],
section_03: [
0x03, // func section
0x02, // 2 bytes
0x01, // number of functions
0x00 // filter
],
section_07: [
0x07, // export section
0x0a, // 10 bytes
0x01, // number of exports
0x06, // 6 byte name
0x66, // f
0x69, // i
0x6c, // l
0x74, // t
0x65, // e
0x72, // r
0x00, // function
0x00 // filter
],
section_0a: [
0x0a, // code section
0x4b, // 75 bytes
0x01, // number of function
0x49, // 73 bytes filter
0x00, // no extra local var
0x20, 0x00, // local.get
0x41, 0xff, 0x01, // mask for r i32.const 0x000000ff
0x71, // i32.and
0xb3, // f32.convert_i32_u
0x43, 0x6c, 0x09, 0x99, 0x3e, // f32.const 0.2989
0x94, // f32.mul
0x20, 0x00, // local.get
0x41, 0x80, 0xfe, 0x03, // mask for g i32.const 0x0000ff00
0x71, // i32.and
0x41, 0x08, 0x76, // right shift two bytes
0xb3, // f32.convert_i32_u
0x43, 0xa2, 0x45, 0x16, 0x3f, // f32.const 0.5870
0x94, // f32.mul
0x92, // f32.add
0x20, 0x00, // local.get
0x41, 0x80, 0x80, 0xfc, 0x07, // mask for b i32.const 0x00ff0000
0x71, // i32.and
0x41, 0x10, 0x76, // right shift four bytes
0xb3, // f32.convert_i32_u
0x43, 0xd5, 0x78, 0xe9, 0x3d, // f32.const 0.1140
0x94, // f32.mul
0x92, // f32.add
0xa9, // i32.trunc_f32_u
0x22, 0x00, // local.tee (add r channel)
0x20, 0x00, // local.get
0x41, 0x08, 0x74, 0x6a, // add g channel
0x20, 0x00, // local.get
0x41, 0x10, 0x74, 0x6a, // add b channel
0x41, 0x80, 0x80, 0x80, 0x78, // a i32.const 0xff000000
0x6a, // add a channel
0x0b // opcode for end
]
};
grayscale_filter.wasm = new Uint8Array(
magic.concat(version)
.concat(grayscale_filter.section_01)
.concat(grayscale_filter.section_03)
.concat(grayscale_filter.section_07)
.concat(grayscale_filter.section_0a)
);
alpha_filter.module = await WebAssembly.compile(alpha_filter.wasm.buffer);
alpha_filter.importObject = { };
alpha_filter.instance = await WebAssembly.instantiate(
alpha_filter.module,
alpha_filter.importObject);
grayscale_filter.module = await WebAssembly.compile(grayscale_filter.wasm.buffer);
grayscale_filter.importObject = { };
grayscale_filter.instance = await WebAssembly.instantiate(
grayscale_filter.module,
grayscale_filter.importObject);
main.module = await WebAssembly.compile(main.wasm.buffer);
main.importObject = {
j: {
m: mem,
alpha: alpha_filter.instance.exports.filter,
grayscale: grayscale_filter.instance.exports.filter
}
};
main.instance = await WebAssembly.instantiate(
main.module,
main.importObject);
setTimeout(() => {
main.instance.exports.alpha(
4 * Math.floor(0x80 * 0x80 / 3),
4 * Math.floor(2 * 0x80 * 0x80 / 3));
canvas_render();
}, 1000);
setTimeout(() => {
main.instance.exports.grayscale(
4 * Math.floor(2 * 0x80 * 0x80 / 3),
4 * Math.floor(0x80 * 0x80 - 2));
canvas_render();
}, 2000);
canvas_render();
hexdump();