Add check for processor endianness. Fix a small warning.

common.h

@@ -2,6 +2,7 @@
 #define _COMMON_H
 
 #include <stdint.h>
+#include <endian.h>
 #include <sys/socket.h>
 #include <libconfig.h>
 
@@ -116,6 +117,7 @@ uint64_t get_absolute_time_in_fp(void);
 
 // this is for reading an unsigned 32 bit number, such as an RTP timestamp
 
+long endianness;
 uint32_t uatoi(const char *nptr);
 
 shairport_cfg config;

player.c

@@ -384,9 +384,9 @@ int32_t rand_in_range(int32_t exclusive_range_limit) {
 }
 
 static inline short dithered_vol(short sample) {
-  int32_t out;
+  long out;
 
-  out = (int32_t)sample * fix_volume;
+  out = (long)sample * fix_volume;
   if (fix_volume < 0x10000) {
   
   	// add a TPDF dither -- see http://www.users.qwest.net/%7Evolt42/cadenzarecording/DitherExplained.pdf
@@ -398,7 +398,7 @@ static inline short dithered_vol(short sample) {
   	// See the original paper at http://www.ece.rochester.edu/courses/ECE472/resources/Papers/Lipshitz_1992.pdf
   	// by Lipshitz, Wannamaker and Vanderkooy, 1992.
   	
-  	int32_t tpdf = rand_in_range(65536+1) - rand_in_range(65536+1);
+  	long tpdf = rand_in_range(65536+1) - rand_in_range(65536+1);
   	// Check there's no clipping -- if there is, 
   	if (tpdf>=0) {
   		if (LONG_MAX-tpdf>=out)
@@ -415,35 +415,6 @@ static inline short dithered_vol(short sample) {
   return out >> 16;
 }
 
-
-/*
-static inline short lcg_rand(void) {
-  static unsigned long lcg_prev = 12345;
-  lcg_prev = lcg_prev * 69069 + 3;
-  return lcg_prev & 0xffff;
-}
-
-
-static inline short dithered_vol(short sample) {
-  static short rand_a;
-  short rand_b;
-  long out;
-
-  out = (long)sample * fix_volume;
-  if (fix_volume < 0x10000) {
-  	// add a TPDF dither -- see http://www.users.qwest.net/%7Evolt42/cadenzarecording/DitherExplained.pdf
-  	// and the discussion around https://www.hydrogenaud.io/forums/index.php?showtopic=16963&st=25
-  	// I think it's wrong. I think, for a 32 --> 16 bits, the range of
-  	// random numbers needs to be from 0 to 2^16, i.e. from 0 to 65536, not from -32768bto +32767
-    rand_b = rand_a;
-    rand_a = lcg_rand();
-    out += rand_a;
-    out -= rand_b;
-  }
-  return out >> 16;
-}
-*/
-
 // get the next frame, when available. return 0 if underrun/stream reset.
 static abuf_t *buffer_get_frame(void) {
   int16_t buf_fill;

shairport.c

@@ -641,6 +641,27 @@ int main(int argc, char **argv) {
   free(basec);
 
   // set defaults
+  
+  
+  // get thje endianness
+  union {
+   uint32_t u32;
+   uint8_t arr[4];
+  } xn;
+
+  xn.arr[0] = 0x44;     /* Lowest-address byte */
+  xn.arr[1] = 0x33;
+  xn.arr[2] = 0x22;
+  xn.arr[3] = 0x11;     /* Highest-address byte */
+  
+  if (xn.u32==0x11223344)
+    endianness = __LITTLE_ENDIAN;
+  else if (xn.u32==0x33441122)
+    endianness = __PDP_ENDIAN;
+  else if (xn.u32==0x44332211)
+    endianness = __BIG_ENDIAN;
+  else die("Can not recognise the endianness of the processor.");
+  
   strcpy(configuration_file_path, "/etc/");
   strcat(configuration_file_path, appName);
   strcat(configuration_file_path, ".conf");
@@ -832,6 +853,18 @@ int main(int argc, char **argv) {
 
   daemon_log(LOG_NOTICE, "startup");
   
+  switch (endianness) {
+    case __LITTLE_ENDIAN:
+      debug(2,"The processor is running little-endian.");
+      break;
+    case __BIG_ENDIAN:
+      debug(2,"The processor is running big-endian.");
+      break;
+    case __PDP_ENDIAN:
+      debug(2,"The processor is running pdp-endian.");
+      break; 
+  }
+  
   /* Mess around with the latency options */
   // Basically, we used to rely on static latencies -- 99400 for iTunes 10 or later and forkedDaapd, 88200 for everything else
   // Nowadays we allow the source to set the latency, which works out at 99651 for iTunes 10 and forkedDaapd and 88220 for everything else