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// Let's calculate zero in some elaborate ways.
function testFancyZeroOffset(fancyZero, memType = 'i32') {
try {
const { mem } = wasmEvalText(`(module
(memory (export "mem") ${memType} 1)
(data (offset ${fancyZero}) "hi")
)`).exports;
const str = String.fromCharCode(...new Uint8Array(mem.buffer).slice(0, 2));
assertEq(str, 'hi');
} catch (e) {
const { getOffset } = wasmEvalText(`(module
(func (export "getOffset") (result ${memType})
${fancyZero}
)
)`).exports;
console.log('Computed offset:', getOffset());
throw e;
}
}
// Do plus one minus one a thousand times
testFancyZeroOffset('i32.const 0 ' + (
'(i32.add (i32.const 1)) '
+ '(i32.sub (i32.const 1)) '
).repeat(1000));
// Do some jank fibonacci
{
let fib = '(i32.const 1)\n'
let a = 1; let b = 1; let next;
for (let i = 0; i < 45; i++) {
fib += `(i32.const ${a})\n`;
fib += '(i32.add)\n';
next = a + b;
a = b;
b = next;
}
fib += `(i32.sub (i32.const ${next}))\n`;
testFancyZeroOffset(fib);
}
// Run the collatz conjecture as long as possible
{
let val = 837799; // should reach 1 in 524 steps
let expr = `(i32.const ${val})\n`;
while (val != 1) {
if (val % 2 == 0) {
expr += `(i32.sub (i32.const ${val / 2}))\n`; // we can't divide in constant expressions lol
val /= 2;
} else {
expr += `(i32.mul (i32.const 3))\n`;
expr += `(i32.add (i32.const 1))\n`;
val = val * 3 + 1;
}
}
expr += `(i32.sub (i32.const 1))\n`;
testFancyZeroOffset(expr);
}
// The collatz conjecture would be even more fun with 64-bit numbers...
if (wasmMemory64Enabled()) {
let val = 1899148184679; // should reach 1 in 1411 steps
let expr = `(i64.const ${val})\n`;
while (val != 1) {
if (val % 2 == 0) {
expr += `(i64.sub (i64.const ${val / 2}))\n`; // we can't divide in constant expressions lol
val /= 2;
} else {
expr += `(i64.mul (i64.const 3))\n`;
expr += `(i64.add (i64.const 1))\n`;
val = val * 3 + 1;
}
}
expr += `(i64.sub (i64.const 1))\n`;
testFancyZeroOffset(expr, 'i64');
}