First step in integrating Rob Janssen's new macros.

1 files changed, 42 insertions, 0 deletions

diff --git a/bits.h b/bits.h
new file mode 100644
index 00000000..1dcea658
--- /dev/null
+++ b/bits.h
@@ -0,0 +1,42 @@
+/*
+ * bits.h - extract binary data from message buffer
+ *
+ * these macros extract bytes, words, longwords, floats or doubles from
+ * a message that contains these items in MSB-first byte order.
+ *
+ * the macros access a local buffer named "buf" which must be declared
+ * as unsigned char buf[SIZE];
+ *
+ * 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.  it looks like 64bit systems with
+ * gcc are OK.
+ */
+
+union int_float {
+    int i;
+    float f;
+};
+
+union long_double {
+    long long l;
+    double d;
+};
+
+#define getsb(off)	((char)buf[off])
+#define getub(off)	(buf[off])
+#define getsw(off)	((short)(((unsigned)getub(off) << 8) | (unsigned)getub(off+1)))
+#define getuw(off)	((unsigned short)(((unsigned)getub(off) << 8) | (unsigned)getub(off+1)))
+#define getsl(off)	((int)(((unsigned)getuw(off) << 16) | getuw(off+2)))
+#define getul(off)	((unsigned int)(((unsigned)getuw(off) << 16) | getuw(off+2)))
+#define getsL(off)	((long long)(((unsigned long long)getul(off) << 32) | getul(off+4)))
+#define getuL(off)	((unsigned long long)(((unsigned long long)getul(off) << 32) | getul(off+4)))
+#define getf(off)	(i_f.i = getsl(off), i_f.f)
+#define getd(off)	(l_d.l = getsL(off), l_d.d)