From 20d8ea1c2d4472ba878fec217f01da875e0ee0f5 Mon Sep 17 00:00:00 2001
From: Hannes <hannes@BRUTUS.HOME>
Date: Fri, 13 Jan 2012 11:52:52 +0100
Subject: [PATCH] Added a ulawdecoder.

---
 headeredit.cpp | 17 ++++++++++++++---
 ulaw_decode.h  |  9 +++++++++
 2 files changed, 23 insertions(+), 3 deletions(-)
 create mode 100644 ulaw_decode.h

diff --git a/headeredit.cpp b/headeredit.cpp
index 5618a08..59db65a 100644
--- a/headeredit.cpp
+++ b/headeredit.cpp
@@ -4,11 +4,11 @@
 #include <cstring>
 #include <cstdlib>
 
-
+signed short decode(unsigned char t);
 main()
 {
   std::vector<unsigned char> data;
-  FILE* f = fopen("outputfileulaw.wav", "rb");
+  FILE* f = fopen("outputfileulaw.raw", "rb");
   rewind(f);
   while(!feof(f))
   {
@@ -16,7 +16,7 @@ main()
     fread(&s, sizeof s, 1, f);
     data.push_back(s);
   }
-  FILE* o = fopen("outputfileulaw.raw", "wb");
+  FILE* o = fopen("outputfileulaw.dec", "wb");
   int headersize = 4;
   int old_header_size = 58;
   unsigned int samples = data.size() - old_header_size;
@@ -37,4 +37,15 @@ main()
   //memcpy(&new_data[0], &samples, sizeof(int));
   memcpy(&new_data[4], &data[old_header_size], samples_old);
   fwrite(&new_data[0], sizeof(unsigned char), samples_old+headersize, o);
+  
+}
+
+signed short decode(unsigned char t)
+{
+  int exp = 0x8 - (0x7 & (t >> 4));
+  int base = (0x1 << (exp+ 5)) - 34;
+  int step = 0x1 << exp;
+  signed short ret = base - step  * (0xf & t);
+  ret = -ret - 1 +  (2 * ret + 1) * (t >> 7);
+  return ret;
 }
\ No newline at end of file
diff --git a/ulaw_decode.h b/ulaw_decode.h
new file mode 100644
index 0000000..99d86ac
--- /dev/null
+++ b/ulaw_decode.h
@@ -0,0 +1,9 @@
+ signed short decode(unsigned char t)
+{
+  int exp = 0x8 - (0x7 & (t >> 4));
+  int base = (0x1 << (exp+ 5)) - 34;
+  int step = 0x1 << exp;
+  signed short ret = base - step  * (0xf & t);
+  ret = -ret - 1 +  (2 * ret + 1) * (t >> 7);
+  return ret;
+}
\ No newline at end of file