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-rw-r--r--erts/doc/src/erlang.xml31
-rw-r--r--erts/emulator/beam/atom.names3
-rw-r--r--erts/emulator/beam/bif.c68
-rw-r--r--erts/emulator/beam/bif.tab1
-rw-r--r--erts/emulator/beam/sys.h3
-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
-rw-r--r--erts/emulator/test/num_bif_SUITE.erl45
-rw-r--r--erts/preloaded/src/erlang.erl13
-rw-r--r--lib/stdlib/src/erl_internal.erl1
11 files changed, 318 insertions, 16 deletions
diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml
index 1d67be2e52..95862216b8 100644
--- a/erts/doc/src/erlang.xml
+++ b/erts/doc/src/erlang.xml
@@ -968,6 +968,37 @@ true
</desc>
</func>
<func>
+ <name>float_to_list(Float, Options) -> string()</name>
+ <fsummary>Text representation of a float formatted using given options</fsummary>
+ <type>
+ <v>Float = float()</v>
+ <v>Options = [Option]</v>
+ <v>Option = {decimals, Decimals::0..249} |
+ {scientific, Decimals::0..249} |
+ compact</v>
+ </type>
+ <desc>
+ <p>Returns a string which corresponds to the text
+ representation of <c>Float</c> using fixed decimal point formatting.
+ When <c>decimals</c> option is specified
+ the returned value will contain at most <c>Decimals</c> number of
+ digits past the decimal point. If the number doesn't fit in the
+ internal static buffer of 256 bytes, the function throws <c>badarg</c>.
+ When <c>compact</c> option is provided
+ the trailing zeros at the end of the list are truncated (this option is
+ only meaningful together with the <c>decimals</c> option). When
+ <c>scientific</c> option is provided, the float will be formatted using
+ scientific notation with <c>Decimals</c> digits of precision. If
+ <c>Options</c> is <c>[]</c> the function behaves like <c>float_to_list/1</c>.
+ </p>
+ <pre>
+> <input>float_to_list(7.12, [{decimals, 4}]).</input>
+"7.1200"
+> <input>float_to_list(7.12, [{decimals, 4}, compact]).</input>
+"7.12"</pre>
+ </desc>
+ </func>
+ <func>
<name name="fun_info" arity="1"/>
<fsummary>Information about a fun</fsummary>
<desc>
diff --git a/erts/emulator/beam/atom.names b/erts/emulator/beam/atom.names
index c47a608215..b74e2785e5 100644
--- a/erts/emulator/beam/atom.names
+++ b/erts/emulator/beam/atom.names
@@ -144,6 +144,7 @@ atom close
atom closed
atom code
atom command
+atom compact
atom compat_rel
atom compile
atom compressed
@@ -165,6 +166,7 @@ atom current_location
atom current_stacktrace
atom data
atom debug_flags
+atom decimals
atom delay_trap
atom dexit
atom depth
@@ -480,6 +482,7 @@ atom scheduler
atom scheduler_id
atom schedulers_online
atom scheme
+atom scientific
atom scope
atom sensitive
atom sequential_tracer
diff --git a/erts/emulator/beam/bif.c b/erts/emulator/beam/bif.c
index 97c8114437..182129cd36 100644
--- a/erts/emulator/beam/bif.c
+++ b/erts/emulator/beam/bif.c
@@ -2917,7 +2917,73 @@ BIF_RETTYPE float_to_list_1(BIF_ALIST_1)
need = i*2;
hp = HAlloc(BIF_P, need);
BIF_RET(buf_to_intlist(&hp, fbuf, i, NIL));
- }
+}
+
+BIF_RETTYPE float_to_list_2(BIF_ALIST_2)
+{
+ const static int arity_two = make_arityval(2);
+ int decimals = SYS_DEFAULT_FLOAT_DECIMALS;
+ int compact = 0;
+ enum fmt_type_ {
+ FMT_LEGACY,
+ FMT_FIXED,
+ FMT_SCIENTIFIC
+ } fmt_type = FMT_LEGACY;
+ Eterm list = BIF_ARG_2;
+ Eterm arg;
+ int i;
+ Uint need;
+ Eterm* hp;
+ FloatDef f;
+ char fbuf[256];
+
+ /* check the arguments */
+ if (is_not_float(BIF_ARG_1))
+ goto badarg;
+
+ for(; is_list(list); list = CDR(list_val(list))) {
+ arg = CAR(list_val(list));
+ if (arg == am_compact) {
+ compact = 1;
+ continue;
+ } else if (is_tuple(arg)) {
+ Eterm* tp = tuple_val(arg);
+ if (*tp == arity_two && is_small(tp[2])) {
+ decimals = signed_val(tp[2]);
+ if (decimals > 0 && decimals < sizeof(fbuf) - 6 /* "X." ++ "e+YY" */)
+ switch (tp[1]) {
+ case am_decimals:
+ fmt_type = FMT_FIXED;
+ continue;
+ case am_scientific:
+ fmt_type = FMT_SCIENTIFIC;
+ continue;
+ }
+ }
+ }
+ goto badarg;
+ }
+ if (is_not_nil(list)) {
+ goto badarg;
+ }
+
+ GET_DOUBLE(BIF_ARG_1, f);
+
+ if (fmt_type == FMT_FIXED) {
+ if ((i = sys_double_to_chars_fast(f.fd, fbuf, sizeof(fbuf),
+ decimals, compact)) <= 0)
+ goto badarg;
+ } else {
+ if ((i = sys_double_to_chars_ext(f.fd, fbuf, sizeof(fbuf), decimals)) <= 0)
+ goto badarg;
+ }
+
+ need = i*2;
+ hp = HAlloc(BIF_P, need);
+ BIF_RET(buf_to_intlist(&hp, fbuf, i, NIL));
+badarg:
+ BIF_ERROR(BIF_P, BADARG);
+}
/**********************************************************************/
diff --git a/erts/emulator/beam/bif.tab b/erts/emulator/beam/bif.tab
index 59a91cd40c..a79feb6da3 100644
--- a/erts/emulator/beam/bif.tab
+++ b/erts/emulator/beam/bif.tab
@@ -64,6 +64,7 @@ bif erlang:external_size/1
bif erlang:external_size/2
ubif erlang:float/1
bif erlang:float_to_list/1
+bif erlang:float_to_list/2
bif erlang:fun_info/2
bif erlang:garbage_collect/0
bif erlang:garbage_collect/1
diff --git a/erts/emulator/beam/sys.h b/erts/emulator/beam/sys.h
index 898a30b010..cecaff54a4 100644
--- a/erts/emulator/beam/sys.h
+++ b/erts/emulator/beam/sys.h
@@ -729,9 +729,12 @@ char * getenv_string(GETENV_STATE *);
void fini_getenv_state(GETENV_STATE *);
/* xxxP */
+#define SYS_DEFAULT_FLOAT_DECIMALS 20
void init_sys_float(void);
int sys_chars_to_double(char*, double*);
int sys_double_to_chars(double, char*, size_t);
+int sys_double_to_chars_ext(double, char*, size_t, size_t);
+int sys_double_to_chars_fast(double, char*, int, int, int);
void sys_get_pid(char *, size_t);
/* erts_sys_putenv() returns, 0 on success and a value != 0 on failure. */
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++;
diff --git a/erts/emulator/test/num_bif_SUITE.erl b/erts/emulator/test/num_bif_SUITE.erl
index 4459732257..7a045484cf 100644
--- a/erts/emulator/test/num_bif_SUITE.erl
+++ b/erts/emulator/test/num_bif_SUITE.erl
@@ -25,6 +25,7 @@
%% abs/1
%% float/1
%% float_to_list/1
+%% float_to_list/2
%% integer_to_list/1
%% list_to_float/1
%% list_to_integer/1
@@ -114,14 +115,46 @@ t_float(Config) when is_list(Config) ->
ok.
-%% Tests float_to_list/1.
+%% Tests float_to_list/1, float_to_list/2.
t_float_to_list(Config) when is_list(Config) ->
- ?line test_ftl("0.0e+0", 0.0),
- ?line test_ftl("2.5e+1", 25.0),
- ?line test_ftl("2.5e+0", 2.5),
- ?line test_ftl("2.5e-1", 0.25),
- ?line test_ftl("-3.5e+17", -350.0e15),
+ test_ftl("0.0e+0", 0.0),
+ test_ftl("2.5e+1", 25.0),
+ test_ftl("2.5e+0", 2.5),
+ test_ftl("2.5e-1", 0.25),
+ test_ftl("-3.5e+17", -350.0e15),
+ "1.00000000000000000000e+00" = float_to_list(1.0),
+ "1.00000000000000000000e+00" = float_to_list(1.0, []),
+ "-1.00000000000000000000e+00" = float_to_list(-1.0, []),
+ "-1.00000000000000000000" = float_to_list(-1.0, [{decimals, 20}]),
+ {'EXIT', {badarg, _}} = (catch float_to_list(1.0, [{decimals, -1}])),
+ {'EXIT', {badarg, _}} = (catch float_to_list(1.0, [{decimals, 250}])),
+ {'EXIT', {badarg, _}} = (catch float_to_list(1.0e+300, [{decimals, 1}])),
+ "1.0e+300" = float_to_list(1.0e+300, [{scientific, 1}]),
+ "1.0" = float_to_list(1.0, [{decimals, 249}, compact]),
+ Expected = "1." ++ string:copies("0", 249) ++ "e+00",
+ Expected = float_to_list(1.0, [{scientific, 249}, compact]),
+
+ X1 = float_to_list(1.0),
+ X2 = float_to_list(1.0, [{scientific, 20}]),
+ X1 = X2,
+ "1.000e+00" = float_to_list(1.0, [{scientific, 3}]),
+ "1.000" = float_to_list(1.0, [{decimals, 3}]),
+ "1.0" = float_to_list(1.0, [{decimals, 3}, compact]),
+ "1.12" = float_to_list(1.123, [{decimals, 2}]),
+ "1.123" = float_to_list(1.123, [{decimals, 3}]),
+ "1.123" = float_to_list(1.123, [{decimals, 3}, compact]),
+ "1.1230" = float_to_list(1.123, [{decimals, 4}]),
+ "1.12300" = float_to_list(1.123, [{decimals, 5}]),
+ "1.123" = float_to_list(1.123, [{decimals, 5}, compact]),
+ "1.1234" = float_to_list(1.1234,[{decimals, 6}, compact]),
+ "2.333333" = erlang:float_to_list(7/3, [{decimals, 6}, compact]),
+ "2.333333" = erlang:float_to_list(7/3, [{decimals, 6}]),
+ "0.00000000000000000000e+00" = float_to_list(0.0, [compact]),
+ "0.0" = float_to_list(0.0, [{decimals, 10}, compact]),
+ "123000000000000000000.0" = float_to_list(1.23e20, [{decimals, 10}, compact]),
+ "1.2300000000e+20" = float_to_list(1.23e20, [{scientific, 10}, compact]),
+ "1.23000000000000000000e+20" = float_to_list(1.23e20, []),
ok.
test_ftl(Expect, Float) ->
diff --git a/erts/preloaded/src/erlang.erl b/erts/preloaded/src/erlang.erl
index 061db72dd8..3a40a6f97d 100644
--- a/erts/preloaded/src/erlang.erl
+++ b/erts/preloaded/src/erlang.erl
@@ -84,7 +84,8 @@
-export([display_nl/0, display_string/1, dist_exit/3, erase/0, erase/1]).
-export([error/1, error/2, exit/1, exit/2, external_size/1]).
-export([external_size/2, finish_after_on_load/2, finish_loading/1, float/1]).
--export([float_to_list/1, fun_info/2, fun_to_list/1, function_exported/3]).
+-export([float_to_list/1, float_to_list/2]).
+-export([fun_info/2, fun_to_list/1, function_exported/3]).
-export([garbage_collect/0, garbage_collect/1]).
-export([garbage_collect_message_area/0, get/0, get/1, get_keys/1]).
-export([get_module_info/1, get_stacktrace/0, group_leader/0]).
@@ -711,6 +712,16 @@ float(_Number) ->
float_to_list(_Float) ->
erlang:nif_error(undefined).
+%% float_to_list/2
+-spec float_to_list(Float, Options) -> string() when
+ Float :: float(),
+ Options :: [Option],
+ Option :: {decimals, non_neg_integer()} |
+ {scientific, non_neg_integer()} |
+ compact.
+float_to_list(_Float, _Options) ->
+ erlang:nif_error(undefined).
+
%% fun_info/2
-spec erlang:fun_info(Fun, Item) -> {Item, Info} when
Fun :: function(),
diff --git a/lib/stdlib/src/erl_internal.erl b/lib/stdlib/src/erl_internal.erl
index 3063881890..bf2fffbd97 100644
--- a/lib/stdlib/src/erl_internal.erl
+++ b/lib/stdlib/src/erl_internal.erl
@@ -278,6 +278,7 @@ bif(exit, 1) -> true;
bif(exit, 2) -> true;
bif(float, 1) -> true;
bif(float_to_list, 1) -> true;
+bif(float_to_list, 2) -> true;
bif(garbage_collect, 0) -> true;
bif(garbage_collect, 1) -> true;
bif(get, 0) -> true;
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-04 12:09:17 +0000