New version of bits.h with fixed-width types for cross-architecture portability.

Also, the bit-getter macros from zodiac.c now live here.

1 files changed, 25 insertions, 21 deletions

diff --git a/bits.h b/bits.h
index 5554a3d7..18bcfebf 100644
--- a/bits.h
+++ b/bits.h
@@ -1,21 +1,17 @@
 /*
  * bits.h - extract binary data from message buffer
- * * These macros extract bytes, words, longwords, floats or doubles from
+ *
+ * These macros extract bytes, words, longwords, floats or doubles from
  * a message that contains these items in MSB-first byte order.
  * By defining the GET_ORIGIN and PUT_ORIGIN macros, it's possible to
  * change the origin of the indexing.
  *
- * assumptions:
+ * Assumptions:
  *  char is 8 bits, short is 16 bits, int is 32 bits, long long is 64 bits,
  *  float is 32 bits IEEE754, double is 64 bits IEEE754.
  *
- * it would be possible to use types like int16_t from header files to enforce
- * these assumptions, but splint does not understand those and will scream.
- * also, using such explicitly sized types usually causes warnings at many
- * other places in a program (like when calling library routines).  we will
- * need to consider this again when we want to port to an architecture which
- * implements differently sized types.  Noth 32- and 64-bit systems with
- * gcc are OK.
+ * The use of fixed-length types in the casts enforces these.
+ * Both 32- and 64-bit systems with gcc are OK with this set.
  */
 
 union int_float {
@@ -31,22 +27,30 @@ union long_double {
 #ifndef GET_ORIGIN
 #define GET_ORIGIN	0
 #endif
-
-#define getsb(buf, off)	((char)buf[GET_ORIGIN+(off)])
-#define getub(buf, off)	(buf[GET_ORIGIN+(off)])
-#define getsw(buf, off)	((short)(((unsigned)getub(buf, off) << 8) | (unsigned)getub(buf, off+1)))
-#define getuw(buf, off)	((unsigned short)(((unsigned)getub(buf, off) << 8) | (unsigned)getub(buf, off+1)))
-#define getsl(buf, off)	((int)(((unsigned)getuw(buf, off) << 16) | getuw(buf, off+2)))
-#define getul(buf, off)	((unsigned int)(((unsigned)getuw(buf, off) << 16) | getuw(buf, off+2)))
-#define getsL(buf, off)	((long long)(((unsigned long long)getul(buf, off) << 32) | getul(buf, off+4)))
-#define getuL(buf, off)	((unsigned long long)(((unsigned long long)getul(buf, off) << 32) | getul(buf, off+4)))
-#define getf(buf, off)	(i_f.i = getsl(buf, off), i_f.f)
-#define getd(buf, off)	(l_d.l = getsL(buf, off), l_d.d)
-
 #ifndef PUT_ORIGIN
 #define PUT_ORIGIN	0
 #endif
 
+/* SiRF and most other GPS protocols use big-endian (network byte order) */
+#define getsb(buf, off)	((int8_t)buf[GET_ORIGIN+(off)])
+#define getub(buf, off)	((u_int8_t)buf[GET_ORIGIN+(off)])
+#define getsw(buf, off)	((int16_t)(((u_int16_t)getub(buf, off) << 8) | (u_int16_t)getub(buf, off+1)))
+#define getuw(buf, off)	((u_int16_t)(((u_int16_t)getub(buf, off) << 8) | (u_int16_t)getub(buf, off+1)))
+#define getsl(buf, off)	((int32_t)(((u_int16_t)getuw(buf, off) << 16) | getuw(buf, off+2)))
+#define getul(buf, off)	((u_int32_t)(((u_int16_t)getuw(buf, off) << 16) | getuw(buf, off+2)))
+#define getsL(buf, off)	((int64_t)(((u_int64_t)getul(buf, off) << 32) | getul(buf, off+4)))
+#define getuL(buf, off)	((u_int64_t)(((u_int64_t)getul(buf, off) << 32) | getul(buf, off+4)))
+#define getf(buf, off)	(i_f.i = getsl(buf, off), i_f.f)
+#define getd(buf, off)	(l_d.l = getsL(buf, off), l_d.d)
+
 #define putbyte(buf,off,b) {buf[PUT_ORIGIN+(off)] = (unsigned char)(b);}
 #define putword(buf,off,w) {putbyte(buf,off,(w) >> 8); putbyte(buf,off+1,w);}
 #define putlong(buf,off,l) {putword(buf,off,(l) >> 16); putword(buf,off+2,l);}
+
+/* Zodiac protocol description uses 1-origin indexing by little-endian word */
+#define getword(n)	( (session->outbuffer[2*(n)-2]) \
+		| (session->outbuffer[2*(n)-1] << 8))
+#define getlong(n)	( (session->outbuffer[2*(n)-2]) \
+		| (session->outbuffer[2*(n)-1] << 8) \
+		| (session->outbuffer[2*(n)+0] << 16) \
+		| (session->outbuffer[2*(n)+1] << 24))