add buffer_ieee754

diff --git a/buffer_ieee754.js b/buffer_ieee754.js
new file mode 100644 (file)
index 0000000..fb295c0
--- /dev/null
+++ b/buffer_ieee754.js
@@ -0,0 +1,84 @@
+exports.readIEEE754 = function(buffer, offset, isBE, mLen, nBytes) {
+  var e, m,
+      eLen = nBytes * 8 - mLen - 1,
+      eMax = (1 << eLen) - 1,
+      eBias = eMax >> 1,
+      nBits = -7,
+      i = isBE ? 0 : (nBytes - 1),
+      d = isBE ? 1 : -1,
+      s = buffer[offset + i];
+
+  i += d;
+
+  e = s & ((1 << (-nBits)) - 1);
+  s >>= (-nBits);
+  nBits += eLen;
+  for (; nBits > 0; e = e * 256 + buffer[offset + i], i += d, nBits -= 8);
+
+  m = e & ((1 << (-nBits)) - 1);
+  e >>= (-nBits);
+  nBits += mLen;
+  for (; nBits > 0; m = m * 256 + buffer[offset + i], i += d, nBits -= 8);
+
+  if (e === 0) {
+    e = 1 - eBias;
+  } else if (e === eMax) {
+    return m ? NaN : ((s ? -1 : 1) * Infinity);
+  } else {
+    m = m + Math.pow(2, mLen);
+    e = e - eBias;
+  }
+  return (s ? -1 : 1) * m * Math.pow(2, e - mLen);
+};
+
+exports.writeIEEE754 = function(buffer, value, offset, isBE, mLen, nBytes) {
+  var e, m, c,
+      eLen = nBytes * 8 - mLen - 1,
+      eMax = (1 << eLen) - 1,
+      eBias = eMax >> 1,
+      rt = (mLen === 23 ? Math.pow(2, -24) - Math.pow(2, -77) : 0),
+      i = isBE ? (nBytes - 1) : 0,
+      d = isBE ? -1 : 1,
+      s = value < 0 || (value === 0 && 1 / value < 0) ? 1 : 0;
+
+  value = Math.abs(value);
+
+  if (isNaN(value) || value === Infinity) {
+    m = isNaN(value) ? 1 : 0;
+    e = eMax;
+  } else {
+    e = Math.floor(Math.log(value) / Math.LN2);
+    if (value * (c = Math.pow(2, -e)) < 1) {
+      e--;
+      c *= 2;
+    }
+    if (e + eBias >= 1) {
+      value += rt / c;
+    } else {
+      value += rt * Math.pow(2, 1 - eBias);
+    }
+    if (value * c >= 2) {
+      e++;
+      c /= 2;
+    }
+
+    if (e + eBias >= eMax) {
+      m = 0;
+      e = eMax;
+    } else if (e + eBias >= 1) {
+      m = (value * c - 1) * Math.pow(2, mLen);
+      e = e + eBias;
+    } else {
+      m = value * Math.pow(2, eBias - 1) * Math.pow(2, mLen);
+      e = 0;
+    }
+  }
+
+  for (; mLen >= 8; buffer[offset + i] = m & 0xff, i += d, m /= 256, mLen -= 8);
+
+  e = (e << mLen) | m;
+  eLen += mLen;
+  for (; eLen > 0; buffer[offset + i] = e & 0xff, i += d, e /= 256, eLen -= 8);
+
+  buffer[offset + i - d] |= s * 128;
+};

diff --git a/index.js b/index.js
index e6f73dbf4c874821ec77f9559200b68e8adb666c..4347b481a59e1872a191d0ad5e436cb872126a81 100644 (file)
--- a/index.js
+++ b/index.js
@@ -860,7 +860,7 @@ function readFloat(buffer, offset, isBigEndian, noAssert) {
         'Trying to read beyond buffer length');
   }
 
-  return require('buffer_ieee754').readIEEE754(buffer, offset, isBigEndian,
+  return require('./buffer_ieee754').readIEEE754(buffer, offset, isBigEndian,
       23, 4);
 }
 
@@ -881,7 +881,7 @@ function readDouble(buffer, offset, isBigEndian, noAssert) {
         'Trying to read beyond buffer length');
   }
 
-  return require('buffer_ieee754').readIEEE754(buffer, offset, isBigEndian,
+  return require('./buffer_ieee754').readIEEE754(buffer, offset, isBigEndian,
       52, 8);
 }
 
@@ -1171,7 +1171,7 @@ function writeFloat(buffer, value, offset, isBigEndian, noAssert) {
     verifIEEE754(value, 3.4028234663852886e+38, -3.4028234663852886e+38);
   }
 
-  require('buffer_ieee754').writeIEEE754(buffer, value, offset, isBigEndian,
+  require('./buffer_ieee754').writeIEEE754(buffer, value, offset, isBigEndian,
       23, 4);
 }
 
@@ -1200,7 +1200,7 @@ function writeDouble(buffer, value, offset, isBigEndian, noAssert) {
     verifIEEE754(value, 1.7976931348623157E+308, -1.7976931348623157E+308);
   }
 
-  require('buffer_ieee754').writeIEEE754(buffer, value, offset, isBigEndian,
+  require('./buffer_ieee754').writeIEEE754(buffer, value, offset, isBigEndian,
       52, 8);
 }