cartodb/node-postgres
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

fixed binaryParsers for small negativ values

Browse Source 
WARNING: bigint support is not correctly working for really big
values. If the value of a integer gets big the number gets fuzzy in
javascript. This is not a limitation of this library.

If you want to handle bigint with the exact value, get it as string
and do not calculate things with it!
This commit is contained in:
Alexander Sulfrian 2011-11-22 04:36:48 +01:00
parent f8962fd036
commit 239d8bd0c2
1 changed files with 17 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
lib/binaryParsers.js
View File

@ -1,8 +1,17 @@
var parseBits = function(data, bits, offset, callback) {
var parseBits = function(data, bits, offset, invert, callback) {
offset = offset || 0;
invert = invert || false;
callback = callback || function(lastValue, newValue, bits) { return (lastValue * Math.pow(2, bits)) + newValue; };
var offsetBytes = offset >> 3;
var inv = function(value) {
if (invert) {
return ~value & 0xff;
}
return value;
};
// read first (maybe partial) byte
var mask = 0xff;
var firstBits = 8 - (offset % 8);
@ -17,19 +26,19 @@ var parseBits = function(data, bits, offset, callback) {
var result = 0;
if ((offset % 8) + bits >= 8) {
result = callback(0, data[offsetBytes] & mask, firstBits);
result = callback(0, inv(data[offsetBytes]) & mask, firstBits);
}
// read bytes
var bytes = (bits + offset) >> 3;
for (var i = offsetBytes + 1; i < bytes; i++) {
result = callback(result, data[i], 8);
result = callback(result, inv(data[i]), 8);
}
// bits to read, that are not a complete byte
var lastBits = (bits + offset) % 8;
if (lastBits > 0) {
result = callback(result, data[bytes] >> (8 - lastBits), lastBits);
result = callback(result, inv(data[bytes]) >> (8 - lastBits), lastBits);
}
return result;
@ -60,7 +69,7 @@ var parseFloatFromBits = function(data, precisionBits, exponentBits) {
return lastValue;
};
var mantissa = parseBits(data, precisionBits, exponentBits + 1, parsePrecisionBits);
var mantissa = parseBits(data, precisionBits, exponentBits + 1, false, parsePrecisionBits);
// special cases
if (exponent == (Math.pow(2, exponentBits + 1) - 1)) {
@ -81,7 +90,7 @@ var parseBool = function(value) {
var parseInt16 = function(value) {
if (parseBits(value, 1) == 1) {
return -1 * (Math.pow(2, 15) - parseBits(value, 15, 1));
return -1 * (parseBits(value, 15, 1, true) + 1);
}
return parseBits(value, 15, 1);
@ -89,7 +98,7 @@ var parseInt16 = function(value) {
var parseInt32 = function(value) {
if (parseBits(value, 1) == 1) {
return -1 * (Math.pow(2, 31) - parseBits(value, 31, 1));
return -1 * (parseBits(value, 31, 1, true) + 1);
}
return parseBits(value, 31, 1);
@ -97,7 +106,7 @@ var parseInt32 = function(value) {
var parseInt64 = function(value) {
if (parseBits(value, 1) == 1) {
return -1 * (Math.pow(2, 63) - parseBits(value, 63, 1));
return -1 * (parseBits(value, 63, 1, true) + 1);
}
return parseBits(value, 63, 1);