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-rw-r--r--erts/emulator/sys/common/erl_sys_common_misc.c151
-rw-r--r--erts/emulator/sys/unix/sys_float.c9
-rw-r--r--erts/emulator/sys/win32/sys_float.c9
3 files changed, 161 insertions, 8 deletions
diff --git a/erts/emulator/sys/common/erl_sys_common_misc.c b/erts/emulator/sys/common/erl_sys_common_misc.c
index 461e763f03..d22914acea 100644
--- a/erts/emulator/sys/common/erl_sys_common_misc.c
+++ b/erts/emulator/sys/common/erl_sys_common_misc.c
@@ -105,3 +105,154 @@ int erts_get_native_filename_encoding(void)
{
return filename_encoding;
}
+
+/* For internal use by sys_double_to_chars_fast() */
+static char* float_first_trailing_zero(char* p)
+{
+ for (--p; *p == '0' && *(p-1) == '0'; --p);
+ if (*(p-1) == '.') ++p;
+ return p;
+}
+
+int
+sys_double_to_chars(double fp, char *buffer, size_t buffer_size)
+{
+ return sys_double_to_chars_ext(fp, buffer, buffer_size, SYS_DEFAULT_FLOAT_DECIMALS);
+}
+
+int
+sys_double_to_chars_fast(double f, char *outbuf, int maxlen, int decimals, int compact)
+{
+ enum {
+ FRAC_SIZE = 52
+ , EXP_SIZE = 11
+ , EXP_MASK = (1ll << EXP_SIZE) - 1
+ , FRAC_MASK = (1ll << FRAC_SIZE) - 1
+ , FRAC_MASK2 = (1ll << (FRAC_SIZE + 1)) - 1
+ , MAX_FLOAT = 1ll << (FRAC_SIZE+1)
+ };
+
+ long long mantissa, int_part, int_part2, frac_part;
+ short exp;
+ int sign, i, n, m, max;
+ double absf;
+ union { long long L; double F; } x;
+ char c, *p = outbuf;
+ int digit, roundup;
+
+ x.F = f;
+
+ exp = (x.L >> FRAC_SIZE) & EXP_MASK;
+ mantissa = x.L & FRAC_MASK;
+ sign = x.L >= 0 ? 1 : -1;
+ if (exp == EXP_MASK) {
+ if (mantissa == 0) {
+ if (sign == -1)
+ *p++ = '-';
+ *p++ = 'i';
+ *p++ = 'n';
+ *p++ = 'f';
+ } else {
+ *p++ = 'n';
+ *p++ = 'a';
+ *p++ = 'n';
+ }
+ *p = '\0';
+ return p - outbuf;
+ }
+
+ exp -= EXP_MASK >> 1;
+ mantissa |= (1ll << FRAC_SIZE);
+ frac_part = 0;
+ int_part = 0;
+ absf = f * sign;
+
+ /* Don't bother with optimizing too large numbers and decimals */
+ if (absf > MAX_FLOAT || decimals > maxlen-17) {
+ int len = erts_snprintf(outbuf, maxlen, "%.*f", decimals, f);
+ if (len >= maxlen)
+ return -1;
+ p = outbuf + len;
+ /* Delete trailing zeroes */
+ if (compact)
+ p = float_first_trailing_zero(outbuf + len);
+ *p = '\0';
+ return p - outbuf;
+ }
+
+ if (exp >= FRAC_SIZE)
+ int_part = mantissa << (exp - FRAC_SIZE);
+ else if (exp >= 0) {
+ int_part = mantissa >> (FRAC_SIZE - exp);
+ frac_part = (mantissa << (exp + 1)) & FRAC_MASK2;
+ }
+ else /* if (exp < 0) */
+ frac_part = (mantissa & FRAC_MASK2) >> -(exp + 1);
+
+ if (int_part == 0) {
+ if (sign == -1)
+ *p++ = '-';
+ *p++ = '0';
+ } else {
+ int ret;
+ while (int_part != 0) {
+ int_part2 = int_part / 10;
+ *p++ = (char)(int_part - ((int_part2 << 3) + (int_part2 << 1)) + '0');
+ int_part = int_part2;
+ }
+ if (sign == -1)
+ *p++ = '-';
+ /* Reverse string */
+ ret = p - outbuf;
+ for (i = 0, n = ret/2; i < n; i++) {
+ int j = ret - i - 1;
+ c = outbuf[i];
+ outbuf[i] = outbuf[j];
+ outbuf[j] = c;
+ }
+ }
+ if (decimals != 0)
+ *p++ = '.';
+
+ max = maxlen - (p - outbuf) - 1 /* leave room for trailing '\0' */;
+ if (max > decimals)
+ max = decimals;
+ for (m = 0; m < max; m++) {
+ /* frac_part *= 10; */
+ frac_part = (frac_part << 3) + (frac_part << 1);
+
+ *p++ = (char)((frac_part >> (FRAC_SIZE + 1)) + '0');
+ frac_part &= FRAC_MASK2;
+ }
+
+ roundup = 0;
+ /* Rounding - look at the next digit */
+ frac_part = (frac_part << 3) + (frac_part << 1);
+ digit = (frac_part >> (FRAC_SIZE + 1));
+ if (digit > 5)
+ roundup = 1;
+ else if (digit == 5) {
+ frac_part &= FRAC_MASK2;
+ if (frac_part != 0) roundup = 1;
+ }
+ if (roundup) {
+ char d;
+ int pos = p - outbuf - 1;
+ do {
+ d = outbuf[pos];
+ if (d == '-') break;
+ if (d == '.') continue;
+ if (++d != ':') {
+ outbuf[pos] = d;
+ break;
+ }
+ outbuf[pos] = '0';
+ } while (--pos);
+ }
+
+ /* Delete trailing zeroes */
+ if (compact && *(p - 1) == '0')
+ p = float_first_trailing_zero(--p);
+ *p = '\0';
+ return p - outbuf;
+}
diff --git a/erts/emulator/sys/unix/sys_float.c b/erts/emulator/sys/unix/sys_float.c
index 3fcb4d88dc..6875c17a75 100644
--- a/erts/emulator/sys/unix/sys_float.c
+++ b/erts/emulator/sys/unix/sys_float.c
@@ -735,7 +735,7 @@ void erts_sys_unblock_fpe(int unmasked)
/*
** Convert a double to ascii format 0.dddde[+|-]ddd
- ** return number of characters converted
+ ** return number of characters converted or -1 if error.
**
** These two functions should maybe use localeconv() to pick up
** the current radix character, but since it is uncertain how
@@ -745,11 +745,12 @@ void erts_sys_unblock_fpe(int unmasked)
*/
int
-sys_double_to_chars(double fp, char *buffer, size_t buffer_size)
+sys_double_to_chars_ext(double fp, char *buffer, size_t buffer_size, size_t decimals)
{
char *s = buffer;
-
- (void) erts_snprintf(buffer, buffer_size, "%.20e", fp);
+
+ if (erts_snprintf(buffer, buffer_size, "%.*e", decimals, fp) >= buffer_size)
+ return -1;
/* Search upto decimal point */
if (*s == '+' || *s == '-') s++;
while (ISDIGIT(*s)) s++;
diff --git a/erts/emulator/sys/win32/sys_float.c b/erts/emulator/sys/win32/sys_float.c
index 09dad89140..960edaa7a5 100644
--- a/erts/emulator/sys/win32/sys_float.c
+++ b/erts/emulator/sys/win32/sys_float.c
@@ -114,15 +114,16 @@ sys_chars_to_double(char *buf, double *fp)
/*
** Convert a double to ascii format 0.dddde[+|-]ddd
-** return number of characters converted
+** return number of characters converted or -1 if error.
*/
int
-sys_double_to_chars(double fp, char *buffer, size_t buffer_size)
+sys_double_to_chars_ext(double fp, char *buffer, size_t buffer_size, size_t decimals)
{
char *s = buffer;
-
- (void) erts_snprintf(buffer, buffer_size, "%.20e", fp);
+
+ if (erts_snprintf(buffer, buffer_size, "%.*e", decimals, fp) >= buffer_size)
+ return -1;
/* Search upto decimal point */
if (*s == '+' || *s == '-') s++;
while (isdigit(*s)) s++;
generated by cgit v1.2.3 (git 2.25.1) at 2024-07-15 16:23:53 +0000