From 471479e723157c1a7df2023ab2eea24fa4ca2246 Mon Sep 17 00:00:00 2001
From: "Yukihiro \"Matz\" Matsumoto" <matz@ruby.or.jp>
Date: Fri, 28 Aug 2020 17:33:16 +0900
Subject: Change float representation in `mrb` binary files.

From human readable (ASCII) string representation to binary dump of
IEEE754 in little endian.
---
 src/dump.c | 35 +++++++++++++++++++++--------------
 src/load.c | 26 ++++++++++++++++++--------
 2 files changed, 39 insertions(+), 22 deletions(-)

(limited to 'src')

diff --git a/src/dump.c b/src/dump.c
index 489e70f8a..243278103 100644
--- a/src/dump.c
+++ b/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
diff --git a/src/load.c b/src/load.c
index 2cc0f7557..392a38456 100644
--- a/src/load.c
+++ b/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;
-
-  /* `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);
+  /* dump IEEE754 little endian binary */
+  union {
+    char s[sizeof(double)];
+    double f;
+  } u;
+
+  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
 
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