1 files changed, 105 insertions, 0 deletions
diff --git a/ext/kcar/c_util.h b/ext/kcar/c_util.h
new file mode 100644
index 0000000..624b4b3
--- /dev/null
+++ b/ext/kcar/c_util.h
@@ -0,0 +1,105 @@
+/*
+ * Generic C functions and macros go here, there are no dependencies
+ * on Unicorn internal structures or the Ruby C API in here.
+ */
+
+#ifndef UH_util_h
+#define UH_util_h
+
+#include <unistd.h>
+#include <assert.h>
+
+#define MIN(a,b) (a < b ? a : b)
+#define ARRAY_SIZE(x) (sizeof(x)/sizeof(x[0]))
+
+#ifndef SIZEOF_OFF_T
+#  define SIZEOF_OFF_T 4
+#  warning SIZEOF_OFF_T not defined, guessing 4.  Did you run extconf.rb?
+#endif
+
+#if SIZEOF_OFF_T == 4
+#  define UH_OFF_T_MAX 0x7fffffff
+#elif SIZEOF_OFF_T == 8
+#  if SIZEOF_LONG == 4
+#    define UH_OFF_T_MAX 0x7fffffffffffffffLL
+#  else
+#    define UH_OFF_T_MAX 0x7fffffffffffffff
+#  endif
+#else
+#  error off_t size unknown for this platform!
+#endif /* SIZEOF_OFF_T check */
+
+/*
+ * ragel enforces fpc as a const, and merely casting can make picky
+ * compilers unhappy, so we have this little helper do our dirty work
+ */
+static inline void *deconst(const void *in)
+{
+  union { const void *in; void *out; } tmp;
+
+  tmp.in = in;
+
+  return tmp.out;
+}
+
+static int hexchar2int(int xdigit)
+{
+  if (xdigit >= 'A' && xdigit <= 'F')
+    return xdigit - 'A' + 10;
+  if (xdigit >= 'a' && xdigit <= 'f')
+    return xdigit - 'a' + 10;
+
+  /* Ragel already does runtime range checking for us in Unicorn: */
+  assert(xdigit >= '0' && xdigit <= '9' && "invalid digit character");
+
+  return xdigit - '0';
+}
+
+/*
+ * multiplies +i+ by +base+ and increments the result by the parsed
+ * integer value of +xdigit+.  +xdigit+ is a character byte
+ * representing a number the range of 0..(base-1)
+ * returns the new value of +i+ on success
+ * returns -1 on errors (including overflow)
+ */
+static off_t step_incr(off_t i, int xdigit, const int base)
+{
+  static const off_t max = UH_OFF_T_MAX;
+  const off_t next_max = (max - (max % base)) / base;
+  off_t offset = hexchar2int(xdigit);
+
+  if (offset > (base - 1))
+    return -1;
+  if (i > next_max)
+    return -1;
+  i *= base;
+
+  if ((offset > (base - 1)) || ((max - i) < offset))
+    return -1;
+
+  return i + offset;
+}
+
+/*
+ * parses a non-negative length according to base-10 and
+ * returns it as an off_t value.  Returns -1 on errors
+ * (including overflow).
+ */
+static off_t parse_length(const char *value, size_t length)
+{
+  off_t rv;
+
+  for (rv = 0; length-- && rv >= 0; ++value) {
+    if (*value >= '0' && *value <= '9')
+      rv = step_incr(rv, *value, 10);
+    else
+      return -1;
+  }
+
+  return rv;
+}
+
+#define CONST_MEM_EQ(const_p, buf, len) \
+  ((sizeof(const_p) - 1) == len && !memcmp(const_p, buf, sizeof(const_p) - 1))
+
+#endif /* UH_util_h */