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util: add varInt encoding helper

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This commit is contained in:
Jeff Garzik 2013-08-16 00:56:29 -04:00
parent 21f2784f34
commit e10afb7358
1 changed files with 24 additions and 0 deletions
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24
util/util.js
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@ -299,6 +299,30 @@ var getVarIntSize = exports.getVarIntSize = function getVarIntSize(i) {
}
};
var varIntBuf = exports.varIntBuf = function varIntBuf(n) {
var buf = undefined;
if (n < 253) {
buf = new Buffer(1);
buf.writeUInt8(n, 0);
} else if (n < 0x10000) {
buf = new Buffer(1 + 2);
buf.writeUInt8(253, 0);
buf.writeUInt16LE(n, 1);
} else if (n < 0x100000000) {
buf = new Buffer(1 + 4);
buf.writeUInt8(254, 0);
buf.writeUInt32LE(n, 1);
} else {
throw new Error("quadword not supported");
}
return buf;
};
var varStrBuf = exports.varStrBuf = function varStrBuf(s) {
return Buffer.concat(varIntBuf(s.length), s);
};
// Initializations
exports.NULL_HASH = new Buffer(32).fill(0);
exports.EMPTY_BUFFER = new Buffer(0);