@polkadot/util
Version:
A collection of useful utilities for @polkadot
61 lines • 2.59 kB
JavaScript
;
Object.defineProperty(exports, "__esModule", { value: true });
exports.u8aToNumber = void 0;
/**
* @name u8aToNumber
* @summary Creates a number from a Uint8Array object.
*/
function u8aToNumber(value, { isNegative = false } = {}) {
const count = value.length;
if (isNegative) {
let result = 0;
switch (count) {
case 0:
return 0;
case 1:
result = value[0] ^ 255;
break;
case 2:
result = (value[0] + (value[1] << 8)) ^ 65535;
break;
case 3:
result = (value[0] + (value[1] << 8) + (value[2] << 16)) ^ 16777215;
break;
case 4:
// for the 3rd byte, we don't << 24 - since JS converts all bitwise operators to
// 32-bit, in the case where the top-most bit is set this yields a negative value
result = (value[0] + (value[1] << 8) + (value[2] << 16) + (value[3] * 16777216)) ^ 4294967295;
break;
case 5:
result = ((value[0] + (value[1] << 8) + (value[2] << 16) + (value[3] * 16777216)) ^ 4294967295) + ((value[4] ^ 0xff) * 4294967296);
break;
case 6:
result = ((value[0] + (value[1] << 8) + (value[2] << 16) + (value[3] * 16777216)) ^ 4294967295) + (((value[4] + (value[5] << 8)) ^ 65535) * 4294967296);
break;
default:
throw new Error('Value more than 48-bits cannot be reliably converted');
}
return (result * -1) - 1;
}
switch (count) {
case 0:
return 0;
case 1:
return value[0];
case 2:
return value[0] + (value[1] << 8);
case 3:
return value[0] + (value[1] << 8) + (value[2] << 16);
case 4:
// for the 3rd byte, we don't << 24 - since JS converts all bitwise operators to
// 32-bit, in the case where the top-most bit is set this yields a negative value
return value[0] + (value[1] << 8) + (value[2] << 16) + (value[3] * 16777216);
case 5:
return value[0] + (value[1] << 8) + (value[2] << 16) + ((value[3] + (value[4] << 8)) * 16777216);
case 6:
return value[0] + (value[1] << 8) + (value[2] << 16) + ((value[3] + (value[4] << 8) + (value[5] << 16)) * 16777216);
default:
throw new Error('Value more than 48-bits cannot be reliably converted');
}
}
exports.u8aToNumber = u8aToNumber;