doodle-clz32-gpu.js

const { GPU } = require('./src');
const gpu = new GPU();
// language=GLSL
const clz32 = `float clz32(float x) {
  int _x = int(x);
  _x -= bitwiseAnd(bitwiseSignedRightShift(_x, 1), ${0x55555555});
  _x = bitwiseAnd(bitwiseSignedRightShift(_x, 2), ${0x33333333}) + bitwiseAnd(_x, ${0x33333333});
  _x = bitwiseAnd((bitwiseSignedRightShift(_x, 4) + _x), ${0x0f0f0f0f});
  _x += bitwiseSignedRightShift(_x, 8);
  _x += bitwiseSignedRightShift(_x, 16);
  return float(bitwiseAnd(_x, ${0x0000003f}));
}
`;
function clz32JS() {
  const int numIntBits = sizeof(int) * 8; //compile time constant
  //do the smearing
  x |= x >> 1;
  x |= x >> 2;
  x |= x >> 4;
  x |= x >> 8;
  x |= x >> 16;
  //count the ones
  x -= x >> 1 & 0x55555555;
  x = (x >> 2 & 0x33333333) + (x & 0x33333333);
  x = (x >> 4) + x & 0x0f0f0f0f;
  x += x >> 8;
  x += x >> 16;
  return numIntBits - (x & 0x0000003f); //subtract # of 1s from 32
}
gpu.addNativeFunction('clz32', clz32);
const kernel = gpu.createKernel(function(value) {
  return clz32(value);
}, {
  output: [1],
  pipeline: true,
  immutable: true,
  // debug: true,
});

console.log(Math.clz32(1.5));
console.log(Math.clz32(2));
const result = kernel(2);
const clone1 = result.clone();
const clone2 = clone1.clone();
result.delete();
clone1.clear();
console.log(clone2.toArray());

// Not working and no current hope