From a973e8f4e92bec0bfa132c74880275e4d345c820 Mon Sep 17 00:00:00 2001
From: James Snyder <jbsnyder@fanplastic.org>
Date: Tue, 10 Feb 2009 05:50:48 +0000
Subject: [PATCH] Modification of buf.c so that logsize^2 represents number of
 bytes in buffer. Element byte counts must be a power of 2.

---
 inc/buf.h      |  2 +-
 inc/platform.h |  5 +++++
 src/buf.c      | 34 +++++++++++++++++++++-------------
 src/common.c   |  4 +---
 4 files changed, 28 insertions(+), 17 deletions(-)

diff --git a/inc/buf.h b/inc/buf.h
index 03d21a23..d381335d 100644
--- a/inc/buf.h
+++ b/inc/buf.h
@@ -25,7 +25,7 @@ typedef struct
   u8 logsize;
   volatile u16 wptr, rptr, count;
   t_buf_data *buf;
-  size_t dsize;
+  u8 logdsize;
 } buf_desc;
 
 // Buffer sizes (there are power of 2 to speed up modulo operations)
diff --git a/inc/platform.h b/inc/platform.h
index fbfbb188..2c0e948d 100644
--- a/inc/platform.h
+++ b/inc/platform.h
@@ -230,4 +230,9 @@ u32 platform_eth_get_elapsed_time();
 void* platform_get_first_free_ram( unsigned id );
 void* platform_get_last_free_ram( unsigned id );
 
+// *****************************************************************************
+// Misc support
+
+unsigned int intlog2( unsigned int v );
+
 #endif
diff --git a/src/buf.c b/src/buf.c
index a6ff3a99..76974a08 100644
--- a/src/buf.c
+++ b/src/buf.c
@@ -22,7 +22,11 @@
   static buf_desc buf_desc_uart[ 0 ];
 #endif
 
-static buf_desc buf_desc_adc [ NUM_ADC ];
+#ifdef BUF_ENABLE_ADC
+  static buf_desc buf_desc_adc [ NUM_ADC ];
+#else
+  static buf_desc buf_desc_adc [ 0 ];
+#endif
 
 // NOTE: the order of descriptors here MUST match the order of the BUF_ID_xx
 // enum in inc/buf.h
@@ -33,8 +37,10 @@ static const buf_desc* buf_desc_array[ BUF_ID_TOTAL ] =
 };
 
 // Helper macros
-#define BUF_MOD_INCR( p, m ) p->m = ( p->m + p->dsize ) & ( ( ( u16 )1 << ( p->logsize + ( p->dsize - 1 ) ) ) - 1 )
-#define BUF_REALSIZE( p ) ( ( u16 )1 << p->logsize )
+#define BUF_MOD_INCR( p, m ) p->m = ( p->m + ( ( u16 )1 << p->logdsize ) ) & ( ( ( u16 )1 << ( p->logsize + p->logdsize) ) - 1 )
+#define BUF_REALSIZE( p ) ( ( u16 )1 << ( p->logsize - p->logdsize ) )
+#define BUF_BYTESIZE( p ) ( ( u16 )1 << p->logsize )
+#define BUF_REALDSIZE( p ) ( ( u16 )1 << p->logdsize )
 #define BUF_GETPTR( resid, resnum ) buf_desc *pbuf = ( buf_desc* )buf_desc_array[ resid ] + resnum
 
 // READ16 and WRITE16 macros are here to ensure _atomic_ reads and writes of 
@@ -42,23 +48,25 @@ static const buf_desc* buf_desc_array[ BUF_ID_TOTAL ] =
 #define READ16( p )     p
 #define WRITE16( p, x ) p = x
 
-
-
 // Initialize the buffer of the specified resource
 // resid - resource ID (BUF_ID_UART ...)
 // resnum - resource number (0, 1, 2...)
 // bufsize - new size of the buffer (one of the BUF_SIZE_xxx constants from
-// dsize - number of bytes held by each element
+// dsize - number of bytes held by each element (must be a power of 2)
 //   buf.h, or BUF_SIZE_NONE to disable buffering
 // Returns 1 on success, 0 on failure
 int buf_set( unsigned resid, unsigned resnum, u8 logsize, size_t dsize )
 {
   BUF_GETPTR( resid, resnum );
   
-  pbuf->logsize = logsize;
-  pbuf->dsize = dsize;
+  // Make sure dsize is a power of 2
+  if ( ( dsize = 0 ) || ( dsize & ( dsize - 1 ) ) )
+    return PLATFORM_ERR; 
   
-  if( ( pbuf->buf = ( t_buf_data* )realloc( pbuf->buf, BUF_REALSIZE( pbuf ) * pbuf->dsize ) ) == NULL )
+  pbuf->logsize = logsize;
+  pbuf->logdsize = intlog2( dsize );
+  
+  if( ( pbuf->buf = ( t_buf_data* )realloc( pbuf->buf, BUF_BYTESIZE( pbuf ) ) ) == NULL )
   {
     pbuf->logsize = BUF_SIZE_NONE;
     pbuf->rptr = pbuf->wptr = pbuf->count = 0;
@@ -80,10 +88,10 @@ int buf_write( unsigned resid, unsigned resnum, t_buf_data *data, size_t dsize )
   BUF_GETPTR( resid, resnum );
   
   // Make sure we only add more of same type
-  if (pbuf->dsize != dsize)
+  if ( dsize != BUF_REALDSIZE( pbuf ) )
     return PLATFORM_ERR;
   
-  memcpy(&pbuf->buf[ pbuf->wptr ], data, dsize);
+  memcpy( &pbuf->buf[ pbuf->wptr ], data, dsize );
   
   BUF_MOD_INCR( pbuf, wptr );
   
@@ -133,13 +141,13 @@ int buf_read( unsigned resid, unsigned resnum, t_buf_data *data, size_t dsize  )
   BUF_GETPTR( resid, resnum );
 
   // Make sure buffer contains right type
-  if (pbuf->dsize != dsize)
+  if ( dsize != BUF_REALDSIZE( pbuf ) )
     return PLATFORM_ERR;
   
   if( READ16( pbuf->count ) == 0 )
     return PLATFORM_UNDERFLOW;
     
-  memcpy(data, &pbuf->buf[ pbuf->rptr ], dsize);
+  memcpy( data, &pbuf->buf[ pbuf->rptr ], dsize );
   
   platform_cpu_disable_interrupts();
   pbuf->count --;
diff --git a/src/common.c b/src/common.c
index 79f93ff7..6dfc898f 100644
--- a/src/common.c
+++ b/src/common.c
@@ -71,7 +71,6 @@ static int cmn_recv_helper( unsigned id, s32 timeout )
 {
 #ifdef BUF_ENABLE_UART
   t_buf_data data;
-  int res;
   
   if( buf_is_enabled( BUF_ID_UART, id ) )
   {
@@ -294,5 +293,4 @@ unsigned int intlog2( unsigned int v )
     r++;
   }
   return r;
-}
-
+}
\ No newline at end of file