From d91feeb7909231c5e1b671f49bd0d4993b371cde Mon Sep 17 00:00:00 2001
From: Olaf Bergmann <bergmann@tzi.org>
Date: Sun, 11 Jul 2010 19:56:58 +0200
Subject: [PATCH] Carsten\'s encode functions for pseudo-fp

---
 encode.c | 29 ++++++++---------------------
 encode.h | 23 +++++++++++++++++------
 2 files changed, 25 insertions(+), 27 deletions(-)

diff --git a/encode.c b/encode.c
index 88f6bb45..dc394a4d 100644
--- a/encode.c
+++ b/encode.c
@@ -1,6 +1,6 @@
 /* encode.c -- encoding and decoding of CoAP data types
  *
- * (c) 2010 Olaf Bergmann <bergmann@tzi.org>
+ * (c) 2010 Carsten Bormann
  */
 
 #ifndef NDEBUG
@@ -9,24 +9,11 @@
 
 #include "encode.h"
 
-unsigned int 
-coap_pseudo_encode( unsigned int val ) {
-  unsigned int e = 0;
-
-  if ( val < HIBIT )
-    return val;
-
-  if ( val > MAX_VALUE ) {
-#ifndef NDEBUG
-    fprintf(stderr, "cannot encode value %u\n", val);
-#endif
-    return ( 1 << N ) - 1;
-  }
-  
-  while ( HIBIT < (val & ~0xff) ) {
-    val = val >> 1;
-    e += 1;
-  }
-
-  return (val & ~EMASK) | e;
+/* Carsten suggested this when fls() is not available: */
+int coap_fls(unsigned int i) {
+  int n;
+  for (n = 0; i; n++)
+    i >>= 1;
+  return n;
 }
+
diff --git a/encode.h b/encode.h
index ee68b324..47fe9b3d 100644
--- a/encode.h
+++ b/encode.h
@@ -1,12 +1,16 @@
 /* encode.h -- encoding and decoding of CoAP data types
  *
- * (c) 2010 Olaf Bergmann <bergmann@tzi.org>
+ * (c) 2010 Carsten Bormann
  */
 
 #ifndef _COAP_ENCODE_H_
 #define _COAP_ENCODE_H_
 
-#include "encode.h"
+#if (BSD >= 199103)
+# include <string.h>
+#else
+# include <strings.h>
+#endif
 
 #define N 8
 #define E 4
@@ -15,10 +19,17 @@
 #define MMASK ((1 << N) - 1 - EMASK)
 #define MAX_VALUE ( (1 << N) - (1 << E) ) * (1 << ((1 << E) - 1))
 
-/* internal function, better use macro COAP_PSEUDOFP_ENCODE() instead */
-unsigned int coap_pseudo_encode( unsigned int val );
+#define COAP_PSEUDOFP_DECODE_8_4(r) (r < HIBIT ? r : (r & MMASK) << (r & EMASK))
 
-#define COAP_PSEUDOFP_ENCODE(r) coap_pseudo_encode( (r) )
-#define COAP_PSEUDOFP_DECODE(r) (r < HIBIT ? r : (r & MMASK) << (r & EMASK))
+#if 0
+/* include this only if fls() is not available */
+extern int coap_fls(unsigned int i);
+#else
+#define coap_fls(i) fls(i)
+#endif
+
+/* ls and s must be integer variables */
+#define COAP_PSEUDOFP_ENCODE_8_4_DOWN(v,ls) (v < HIBIT ? v : (ls = coap_fls(v) - N, (v >> ls) & MMASK) + ls)
+#define COAP_PSEUDOFP_ENCODE_8_4_UP(v,ls,s) (v < HIBIT ? v : (ls = coap_fls(v) - N, (s = (((v + ((1<<E<<ls)-1)) >> ls) & MMASK)), s == 0 ? HIBIT + ls + 1 : s + ls))
 
 #endif /* _COAP_ENCODE_H_ */