Change float representation in `mrb` binary files.

From human readable (ASCII) string representation to binary dump of
IEEE754 in little endian.

include/mruby/endian.h

+/**
+** @file mruby/endian.h - detect endian-ness
+**
+** See Copyright Notice in mruby.h
+*/
+
+#ifndef MRUBY_ENDIAN_H
+#define MRUBY_ENDIAN_H
+
+#include <limits.h>
+
+MRB_BEGIN_DECL
+
+#if !defined(BYTE_ORDER) && defined(__BYTE_ORDER__)
+# define BYTE_ORDER __BYTE_ORDER__
+#endif
+#if !defined(BIG_ENDIAN) && defined(__ORDER_BIG_ENDIAN__)
+# define BIG_ENDIAN __ORDER_BIG_ENDIAN__
+#endif
+#if !defined(LITTLE_ENDIAN) && defined(__ORDER_LITTLE_ENDIAN__)
+# define LITTLE_ENDIAN __ORDER_LITTLE_ENDIAN__
+#endif
+
+#ifdef BYTE_ORDER
+# if BYTE_ORDER == BIG_ENDIAN
+#  define littleendian 0
+# elif BYTE_ORDER == LITTLE_ENDIAN
+#  define littleendian 1
+# endif
+#endif
+#ifndef littleendian
+/* can't distinguish endian in compile time */
+static inline int
+check_little_endian(void)
+{
+  unsigned int n = 1;
+  return (*(unsigned char *)&n == 1);
+}
+#  define littleendian check_little_endian()
+#endif
+
+MRB_END_DECL
+
+#endif  /* MRUBY_ENDIAN_H */

mrbgems/mruby-pack/src/pack.c

@@ -9,10 +9,10 @@
 #include "mruby/numeric.h"
 #include "mruby/string.h"
 #include "mruby/variable.h"
+#include "mruby/endian.h"
 
 #include <ctype.h>
 #include <errno.h>
-#include <limits.h>
 #include <string.h>
 
 struct tmpl {
@@ -63,36 +63,6 @@ const static unsigned char base64chars[] =
     "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 static unsigned char base64_dec_tab[128];
 
-#if !defined(BYTE_ORDER) && defined(__BYTE_ORDER__)
-# define BYTE_ORDER __BYTE_ORDER__
-#endif
-#if !defined(BIG_ENDIAN) && defined(__ORDER_BIG_ENDIAN__)
-# define BIG_ENDIAN __ORDER_BIG_ENDIAN__
-#endif
-#if !defined(LITTLE_ENDIAN) && defined(__ORDER_LITTLE_ENDIAN__)
-# define LITTLE_ENDIAN __ORDER_LITTLE_ENDIAN__
-#endif
-
-#ifdef BYTE_ORDER
-# if BYTE_ORDER == BIG_ENDIAN
-#  define littleendian 0
-#  define check_little_endian() (void)0
-# elif BYTE_ORDER == LITTLE_ENDIAN
-#  define littleendian 1
-#  define check_little_endian() (void)0
-# endif
-#endif
-#ifndef littleendian
-/* can't distinguish endian in compile time */
-static int littleendian = 0;
-static void
-check_little_endian(void)
-{
-  unsigned int n = 1;
-  littleendian = (*(unsigned char *)&n == 1);
-}
-#endif
-
 static unsigned int
 hex2int(unsigned char ch)
 {
@@ -1426,7 +1396,6 @@ mrb_pack_unpack1(mrb_state *mrb, mrb_value str)
 void
 mrb_mruby_pack_gem_init(mrb_state *mrb)
 {
-  check_little_endian();
   make_base64_dec_tab();
 
   mrb_define_method(mrb, mrb->array_class, "pack", mrb_pack_pack, MRB_ARGS_REQ(1));

src/dump.c

@@ -12,6 +12,7 @@
 #include <mruby/irep.h>
 #include <mruby/numeric.h>
 #include <mruby/debug.h>
+#include <mruby/endian.h>
 
 #ifndef MRB_NO_FLOAT
 #ifdef MRB_USE_FLOAT32
@@ -89,13 +90,25 @@ write_iseq_block(mrb_state *mrb, const mrb_irep *irep, uint8_t *buf, uint8_t fla
 }
 
 #ifndef MRB_NO_FLOAT
-static mrb_value
-float_to_str(mrb_state *mrb, mrb_float f)
+static void
+dump_float(mrb_state *mrb, uint8_t *buf, mrb_float f)
 {
-  if (isinf(f)) {
-    return f < 0 ? mrb_str_new_lit(mrb, "I") : mrb_str_new_lit(mrb, "i");
+  /* dump IEEE754 binary in little endian */
+  union {
+    double f;
+    char s[sizeof(double)];
+  } u = {.f = (double)f};
+
+  if (littleendian) {
+    memcpy(buf, u.s, sizeof(double));
+  }
+  else {
+    int i;
+
+    for (i=0; i<sizeof(double); i++) {
+      buf[i] = u.s[sizeof(double)-i-1];
+    }
   }
-  return  mrb_float_to_str(mrb, mrb_float_value(mrb, f), MRB_FLOAT_FMT);
 }
 #endif
 
@@ -133,10 +146,7 @@ get_pool_block_size(mrb_state *mrb, const mrb_irep *irep)
     case IREP_TT_FLOAT:
 #ifndef MRB_NO_FLOAT
       {
-        mrb_value str = float_to_str(mrb, irep->pool[pool_no].u.f);
-        mrb_int len = RSTRING_LEN(str);
-        mrb_assert_int_fit(mrb_int, len, size_t, SIZE_MAX);
-        size += (size_t)len;
+        size += sizeof(double);
       }
 #endif
       break;
@@ -194,12 +204,9 @@ write_pool_block(mrb_state *mrb, const mrb_irep *irep, uint8_t *buf)
       cur += uint8_to_bin(IREP_TT_FLOAT, cur); /* data type */
 #ifndef MRB_NO_FLOAT
       {
-        mrb_value str = float_to_str(mrb, irep->pool[pool_no].u.f);
-        ptr = RSTRING_PTR(str);
-        len = RSTRING_LEN(str);
-        mrb_assert_int_fit(mrb_int, len, uint16_t, UINT16_MAX);
+        len = sizeof(double);
         cur += uint16_to_bin((uint16_t)len, cur); /* data length */
-        memcpy(cur, ptr, (size_t)len);
+        dump_float(mrb, cur,irep->pool[pool_no].u.f);
         cur += len;
       }
 #else

src/load.c

@@ -15,6 +15,7 @@
 #include <mruby/debug.h>
 #include <mruby/error.h>
 #include <mruby/data.h>
+#include <mruby/endian.h>
 
 #if SIZE_MAX < UINT32_MAX
 # error size_t must be at least 32 bits wide
@@ -40,17 +41,26 @@ offset_crc_body(void)
 }
 
 #ifndef MRB_NO_FLOAT
-double mrb_str_len_to_dbl(mrb_state *mrb, const char *s, size_t len, mrb_bool badcheck);
-
 static double
 str_to_double(mrb_state *mrb, const char *p, size_t len)
 {
-  /* `i`, `inf`, `infinity` */
-  if (len > 0 && p[0] == 'i') return INFINITY;
+  /* dump IEEE754 little endian binary */
+  union {
+    char s[sizeof(double)];
+    double f;
+  } u;
 
-  /* `I`, `-inf`, `-infinity` */
-  if (p[0] == 'I' || (len > 1 && p[0] == '-' && p[1] == 'i')) return -INFINITY;
-  return mrb_str_len_to_dbl(mrb, p, len, TRUE);
+  mrb_assert(sizeof(double)==len);
+  if (littleendian) {
+    memcpy(u.s, p, sizeof(double));
+  }
+  else {
+    int i;
+    for (i=0; i<sizeof(double); i++) {
+      u.s[i] = p[sizeof(double)-i-1];
+    }
+  }
+  return u.f;
 }
 #endif