From ca8694992ee30198c75f2be2e4455273f0d56439 Mon Sep 17 00:00:00 2001
From: Rob Tillaart <rob.tillaart@gmail.com>
Date: Mon, 30 Sep 2013 17:16:02 +0200
Subject: [PATCH] + initial version

---
 libraries/IEEE754tools/IEEE754tools.h | 226 ++++++++++++++++++++++++++
 1 file changed, 226 insertions(+)
 create mode 100644 libraries/IEEE754tools/IEEE754tools.h

diff --git a/libraries/IEEE754tools/IEEE754tools.h b/libraries/IEEE754tools/IEEE754tools.h
new file mode 100644
index 00000000..87a28a0a
--- /dev/null
+++ b/libraries/IEEE754tools/IEEE754tools.h
@@ -0,0 +1,226 @@
+//
+//    FILE: IEEE754tools.h
+//  AUTHOR: Rob Tillaart
+// VERSION: 0.1.00
+// PURPOSE: IEEE754 tools
+//
+// http://playground.arduino.cc//Main/IEEE754tools
+//
+// Released to the public domain
+// not tested, use with care
+//
+
+#ifndef IEEE754tools_h
+#define IEEE754tools_h
+
+
+#if defined(ARDUINO) && ARDUINO >= 100
+#include "Arduino.h"
+#else
+#include "WProgram.h"
+#endif
+
+// (un)comment lines to configure functionality / size
+//#define IEEE754_ENABLE_MSB
+#define IEEE754_ENABLE_DUMP
+
+// IEEE754 float layout; 
+struct IEEEfloat
+{
+    uint32_t m:23; 
+    uint8_t e:8;
+    uint8_t s:1;
+};
+
+// IEEE754 double layout; 
+struct IEEEdouble
+{
+    uint64_t m:52; 
+    uint16_t e:11;
+    uint8_t s:1;
+};
+
+// Arduino UNO double layout: 
+// the UNO has no 64 bit double, it is only able to map 23 bits of the mantisse
+// a filler is added.
+struct _DBL
+{
+    uint32_t filler:29;
+    uint32_t m:23;
+    uint16_t e:11;
+    uint8_t  s:1;
+};
+
+// for packing and unpacking a float
+typedef union _FLOATCONV
+{
+    IEEEfloat p;
+    float f;
+    byte b[4];
+} _FLOATCONV;
+
+// for packing and unpacking a double
+typedef union _DBLCONV
+{
+    // IEEEdouble p;
+    _DBL p;
+    double d;           // !! is a 32bit float for UNO.
+    byte b[4];
+} _DBLCONV;
+
+
+#ifdef IEEE754_ENABLE_DUMP
+// print float components
+void dumpFloat(float number)
+{
+    IEEEfloat* x = (IEEEfloat*) ((void*)&number);
+    Serial.print(x->s, HEX);
+    Serial.print("\t");
+    Serial.print(x->e, HEX);
+    Serial.print("\t");
+    Serial.println(x->m, HEX);
+    
+    // Serial.print(" sign: "); Serial.print(x->s);
+    // Serial.print("  exp: "); Serial.print(x->e);
+    // Serial.print(" mant: "); Serial.println(x->m);
+}
+
+// print "double" components
+void dumpDBL(struct _DBL dbl)
+{
+    Serial.print(dbl.s, HEX);
+    Serial.print("\t");
+    Serial.print(dbl.e, HEX);
+    Serial.print("\t");
+    Serial.println(dbl.m, HEX);
+}
+#endif
+
+
+//
+// converts a float to a packed array of 8 bytes representing a 64 bit double
+// restriction exponent and mantisse.
+//
+// float;  array of 8 bytes;  LSBFIRST; MSBFIRST
+//
+void float2DoublePacked(float number, byte* bar, int byteOrder=LSBFIRST)  
+{
+    _FLOATCONV fl;
+    fl.f = number;
+    _DBLCONV dbl;
+    dbl.p.s = fl.p.s;
+    dbl.p.e = fl.p.e-127 +1023;  // exponent adjust
+    dbl.p.m = fl.p.m;
+    
+#ifdef IEEE754_ENABLE_MSB
+    if (byteOrder == LSBFIRST)
+    {
+#endif
+        for (int i=0; i<8; i++)
+        {
+            bar[i] = dbl.b[i];
+        }
+#ifdef IEEE754_ENABLE_MSB
+    }
+    else
+    {
+        for (int i=0; i<8; i++)
+        {
+            bar[i] = dbl.b[7-i];
+        }
+    }
+#endif
+}
+
+//
+// converts a packed array of bytes into a 32bit float.
+// there can be an exponent overflow
+// the mantisse is truncated to 23 bits.
+//
+float doublePacked2Float(byte* bar, int byteOrder=LSBFIRST)
+{
+    _FLOATCONV fl;
+    _DBLCONV dbl;
+    
+#ifdef IEEE754_ENABLE_MSB
+    if (byteOrder == LSBFIRST)
+    {
+#endif
+        for (int i=0; i<8; i++)
+        {
+            dbl.b[i] = bar[i];
+        }
+#ifdef IEEE754_ENABLE_MSB
+    }
+    else
+    {
+        for (int i=0; i<8; i++)
+        {
+            dbl.b[i] = bar[7-i];
+        }
+    }
+#endif
+    
+    int e = dbl.p.e-1023+127;  // exponent adjust 
+    // TODO check exponent overflow.
+    if (e >=0 || e <= 255) 
+    {
+        fl.p.s = dbl.p.s;
+        fl.p.e = e;  
+        fl.p.m = dbl.p.m;  // note this one clips the mantisse 
+    }
+    else fl.f = NAN;
+    
+    return fl.f;
+}
+
+//
+// NOT TESTED FUNCTIONS
+// 
+uint8_t getSign(float number)
+{
+  IEEEfloat* x = (IEEEfloat*) ((void*)&number);
+  return x->s;
+}
+
+int getExponent(float number)
+{
+  IEEEfloat* x = (IEEEfloat*) ((void*)&number);
+  return x->e - 127;
+}
+
+uint32_t getMantisse(float number)
+{
+  IEEEfloat* x = (IEEEfloat*) ((void*)&number);
+  return x->m;
+}
+
+/*
+// ONELINERS to speed up some specific 32 bit float math
+
+// *(((byte*) &number)+3) &= 0x7F;              // number == fabs(number);
+// x = *(((byte*) &number)+3) & 0x7F;           // x = fabs(number);
+// GAIN = factor 2
+
+// *(((byte*) &number)+3) |= 0x80;              // number == fabs(number);
+// x = *(((byte*) &number)+3) | 0x80;           // x == -fabs(number);
+// GAIN = factor 2
+
+// *(((byte*) &number)+3) ^= 0x80;              // number = -number;
+// x = *(((byte*) &number)+3) ^ 0x80;           // x = -number;
+// GAIN = factor 2
+
+// s = *(((uint8_t*) &number)+3) & 0x80;        // s = sign(number);
+// if ( *(((byte*) &number)+3) & 0x80) x=2;     // if (number < 0) x=2;
+// GAIN = factor 5
+
+int getExponent(float number)
+{
+    uint8_t e = (*(((uint8_t*) &number)+3) & 0x7F) << 1;
+    if (*(((uint8_t*) &number)+2) & 0x80) e++;
+    return e;
+}
+
+*/
+#endif
+// END OF FILE
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