bits.min.js

var BigInteger=require("big-integer");BigInteger.maxValue=function(nbBits){return BigInteger(1).shiftLeft(nbBits).minus(1)};function validateLayout(layout){if(layout.length==0){throw new Error("Empty layout")}for(var i=0;i<layout.length;i++){var field=layout[i];if(isNaN(field.bits)||field.bits<=0){throw new Error("Invalid bits value in layout field '"+field.name+"': "+"field.bits")}}}function validateObject(layout,object){validateLayout(layout);var keys=Object.keys(object);if(layout.length!=keys.length){throw new Error("Different number of fields in object ("+keys.length+") and layout ("+layout.length+")")}for(var i=0;i<keys.length;i++){var key=keys[i];if(object[key].isNegative()&&!object[key].isZero()){throw new Error("Value for '"+key+"' is negative")}}for(var i=0;i<layout.length;i++){var field=layout[i];if(!object.hasOwnProperty(field.name)){throw new Error("Field '"+field.name+"' not found in object")}var value=object[field.name];var maxValue=BigInteger.maxValue(field.bits);if(value.greater(maxValue)){throw new Error("Invalid value for field '"+field.name+"': "+value.toString()+" > "+maxValue.toString())}}}function validateBigint(layout,bigint){validateLayout(layout);var totalBits=layout.reduce(function(acc,curr){return acc+curr.bits},0);var maxValue=BigInteger.maxValue(totalBits);if(bigint.greater(maxValue)){throw new Error("Packed value is too big for layout (max: "+maxValue.toString()+" actual: "+bigint.toString()+")")}}function encode(layout,object){validateObject(layout,object);var bigint=BigInteger();var currentBit=0;for(var i=0;i<layout.length;i++){var field=layout[i];var value=object[field.name];value=value.shiftLeft(currentBit);bigint=bigint.or(value);currentBit+=field.bits}return bigint}function decode(layout,bigint){validateBigint(layout,bigint);var object={},currentBit=0;for(var i=0;i<layout.length;i++){var field=layout[i];var mask=BigInteger.maxValue(field.bits).shiftLeft(currentBit);var value=bigint.and(mask).shiftRight(currentBit);object[field.name]=value;currentBit+=field.bits}return object}module.exports={encode:encode,decode:decode};