Use internal dtoa/strtod for double conversion

The internal Lua CJSON dtoa/strtod routines have locale support
disabled. This avoids problems under locales with comma decimal
separators.

Build changes:
- CMake: Check for big endian architectures
- Makefile: Provide option to build with dtoa.c

Modifications to dtoa.c:
- Include locale dtoa_config.h configuration
- Rename Infinity/NaN to inf/nan to match common C libraries
- Rename strtod() -> internal_strtod() to prevent conflict with libc
  function

Modifications to g_fmt.c:
- Return output string length (instead of original buffer pointer)
- Provide precision as an argument to g_fmt()
- Silence compilations warnings from vendor source
  - while(a = b)
  - Unused label "done:"
- Only swap to scientific notation when once the number of decimal
  digits required exceeds the precision available. This matches
  standard printf format %g.
- Display a "0" in front of numbers < 1.

1 files changed, 66 insertions, 0 deletions

diff --git a/dtoa_config.h b/dtoa_config.h
new file mode 100644
index 0000000..294351d
--- /dev/null
+++ b/dtoa_config.h
@@ -0,0 +1,66 @@
+#ifndef _DTOA_CONFIG_H
+#define _DTOA_CONFIG_H
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+/* Ensure dtoa.c does not USE_LOCALE. Lua CJSON must not use locale
+ * aware conversion routines. */
+#undef USE_LOCALE
+
+/* dtoa.c should not touch errno, Lua CJSON does not use it, and it
+ * may not be threadsafe */
+#define NO_ERRNO
+
+#define Long    int32_t
+#define ULong   uint32_t
+#define Llong   int64_t
+#define ULLong  uint64_t
+
+#ifdef IEEE_BIG_ENDIAN
+#define IEEE_MC68k
+#else
+#define IEEE_8087
+#endif
+
+#define MALLOC(n)   xmalloc(n)
+
+static void *xmalloc(size_t size)
+{
+    void *p;
+
+    p = malloc(size);
+    if (!p) {
+        fprintf(stderr, "Out of memory");
+        abort();
+    }
+
+    return p;
+}
+
+#ifdef MULTIPLE_THREADS
+
+/* Enable locking to support multi-threaded applications */
+
+#include <pthread.h>
+
+static pthread_mutex_t private_dtoa_lock[2] = {
+    PTHREAD_MUTEX_INITIALIZER,
+    PTHREAD_MUTEX_INITIALIZER
+};
+
+#define ACQUIRE_DTOA_LOCK(n)    do {            \
+    pthread_mutex_lock(&private_dtoa_lock[n]);   \
+} while (0)
+
+#define FREE_DTOA_LOCK(n)   do {                \
+    pthread_mutex_unlock(&private_dtoa_lock[n]); \
+} while (0)
+
+#endif  /* MULTIPLE_THREADS */
+
+#endif  /* _DTOA_CONFIG_H */
+
+/* vi:ai et sw=4 ts=4:
+ */