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Add float_to_binary and binary_to_float
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@garazdawi
garazdawi committed Feb 14, 2013
1 parent b074099 commit 5279b3a
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53 changes: 39 additions & 14 deletions erts/doc/src/erlang.xml
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Original file line number Diff line number Diff line change
Expand Up @@ -299,6 +299,18 @@
<p>Failure: <c>badarg</c> if the atom does not already exist.</p>
</desc>
</func>
<func>
<name name="binary_to_float" arity="1"/>
<fsummary>Convert from text representation to a float</fsummary>
<desc>
<p>Returns the float whose text representation is <c><anno>Binary</anno></c>.</p>
<pre>
> <input>binary_to_float(&lt;&lt;"2.2017764e+0">>).</input>
2.2017764</pre>
<p>Failure: <c>badarg</c> if <c><anno>Binary</anno></c> contains a bad
representation of a float.</p>
</desc>
</func>
<func>
<name name="binary_to_integer" arity="1"/>
<fsummary>Convert from text representation to an integer</fsummary>
Expand Down Expand Up @@ -987,26 +999,38 @@ true
</desc>
</func>
<func>
<name name="float_to_list" arity="1"/>
<name name="float_to_binary" arity="1"/>
<fsummary>Text representation of a float</fsummary>
<desc>
<p>Returns a string which corresponds to the text
representation of <c><anno>Float</anno></c>.</p>
<p>The same as <c>float_to_binary(<anno>Float</anno>,[{scientific,20}])</c>.</p>
</desc>
</func>
<func>
<name name="float_to_binary" arity="2"/>
<fsummary>Text representation of a float formatted using given options</fsummary>
<desc>
<p>Returns a binary which corresponds to the text
representation of <c><anno>Float</anno></c> using fixed decimal
point formatting. The <c><anno>Options</anno></c> behave in the same
way as <seealso marker="#float_to_list/2">float_to_list/2</seealso>.
</p>
<pre>
> <input>float_to_list(7.0).</input>
"7.00000000000000000000e+00"</pre>
> <input>float_to_binary(7.12, [{decimals, 4}]).</input>
&lt;&lt;"7.1200">>
> <input>float_to_binary(7.12, [{decimals, 4}, compact]).</input>
&lt;&lt;"7.12">></pre>
</desc>
</func>
<func>
<name name="float_to_list" arity="1"/>
<fsummary>Text representation of a float</fsummary>
<desc>
<p>The same as <c>float_to_list(<anno>Float</anno>,[{scientific,20}])</c>.</p>
</desc>
</func>
<func>
<name>float_to_list(Float, Options) -> string()</name>
<name name="float_to_list" arity="2"/>
<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..253} |
{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.
Expand All @@ -1019,7 +1043,8 @@ true
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>.
<c>Options</c> is <c>[]</c> the function behaves like
<c><seealso marker="#float_to_list/1">float_to_list/1</seealso></c>.
</p>
<pre>
> <input>float_to_list(7.12, [{decimals, 4}]).</input>
Expand Down
187 changes: 135 additions & 52 deletions erts/emulator/beam/bif.c
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Original file line number Diff line number Diff line change
Expand Up @@ -39,6 +39,7 @@
#include "erl_thr_progress.h"
#define ERTS_PTAB_WANT_BIF_IMPL__
#include "erl_ptab.h"
#include "erl_bits.h"

static Export* flush_monitor_message_trap = NULL;
static Export* set_cpu_topology_trap = NULL;
Expand Down Expand Up @@ -2955,29 +2956,9 @@ BIF_RETTYPE list_to_integer_2(BIF_ALIST_2)

/**********************************************************************/

/* convert a float to a list of ascii characters */
static int do_float_to_charbuf(Process *p, Eterm efloat, Eterm list,
char *fbuf, int sizeof_fbuf) {

BIF_RETTYPE float_to_list_1(BIF_ALIST_1)
{
int i;
Uint need;
Eterm* hp;
FloatDef f;
char fbuf[30];

/* check the arguments */
if (is_not_float(BIF_ARG_1))
BIF_ERROR(BIF_P, BADARG);
GET_DOUBLE(BIF_ARG_1, f);
if ((i = sys_double_to_chars(f.fd, fbuf, sizeof(fbuf))) <= 0)
BIF_ERROR(BIF_P, EXC_INTERNAL_ERROR);
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;
Expand All @@ -2986,16 +2967,11 @@ BIF_RETTYPE float_to_list_2(BIF_ALIST_2)
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))
if (is_not_float(efloat))
goto badarg;

for(; is_list(list); list = CDR(list_val(list))) {
Expand Down Expand Up @@ -3023,22 +2999,64 @@ BIF_RETTYPE float_to_list_2(BIF_ALIST_2)
goto badarg;
}

GET_DOUBLE(BIF_ARG_1, f);
GET_DOUBLE(efloat, f);

if (fmt_type == FMT_FIXED) {
if ((i = sys_double_to_chars_fast(f.fd, fbuf, sizeof(fbuf),
decimals, compact)) <= 0)
goto badarg;
return sys_double_to_chars_fast(f.fd, fbuf, sizeof_fbuf,
decimals, compact);
} else {
if ((i = sys_double_to_chars_ext(f.fd, fbuf, sizeof(fbuf), decimals)) <= 0)
goto badarg;
return sys_double_to_chars_ext(f.fd, fbuf, sizeof_fbuf, decimals);
}

need = i*2;
hp = HAlloc(BIF_P, need);
BIF_RET(buf_to_intlist(&hp, fbuf, i, NIL));
badarg:
return -1;
}

/* convert a float to a list of ascii characters */

static BIF_RETTYPE do_float_to_list(Process *BIF_P, Eterm arg, Eterm opts) {
int used;
Eterm* hp;
char fbuf[256];

if ((used = do_float_to_charbuf(BIF_P,arg,opts,fbuf,sizeof(fbuf))) <= 0) {
BIF_ERROR(BIF_P, BADARG);
}
hp = HAlloc(BIF_P, (Uint)used*2);
BIF_RET(buf_to_intlist(&hp, fbuf, (Uint)used, NIL));
}


BIF_RETTYPE float_to_list_1(BIF_ALIST_1)
{
return do_float_to_list(BIF_P,BIF_ARG_1,NIL);
}

BIF_RETTYPE float_to_list_2(BIF_ALIST_2)
{
return do_float_to_list(BIF_P,BIF_ARG_1,BIF_ARG_2);
}

/* convert a float to a binary of ascii characters */

static BIF_RETTYPE do_float_to_binary(Process *BIF_P, Eterm arg, Eterm opts) {
int used;
char fbuf[256];

if ((used = do_float_to_charbuf(BIF_P,arg,opts,fbuf,sizeof(fbuf))) <= 0) {
BIF_ERROR(BIF_P, BADARG);
}
BIF_RET(new_binary(BIF_P, (byte*)fbuf, (Uint)used));
}

BIF_RETTYPE float_to_binary_1(BIF_ALIST_1)
{
return do_float_to_binary(BIF_P,BIF_ARG_1,NIL);
}

BIF_RETTYPE float_to_binary_2(BIF_ALIST_2)
{
return do_float_to_binary(BIF_P,BIF_ARG_1,BIF_ARG_2);
}

/**********************************************************************/
Expand Down Expand Up @@ -3223,36 +3241,101 @@ BIF_RETTYPE string_to_float_1(BIF_ALIST_1)
BIF_RET(tup);
}

static BIF_RETTYPE do_charbuf_to_float(Process *BIF_P,char *buf) {
FloatDef f;
Eterm res;
Eterm* hp;

if (sys_chars_to_double(buf, &f.fd) != 0)
BIF_ERROR(BIF_P, BADARG);

hp = HAlloc(BIF_P, FLOAT_SIZE_OBJECT);
res = make_float(hp);
PUT_DOUBLE(f, hp);
BIF_RET(res);

}

BIF_RETTYPE list_to_float_1(BIF_ALIST_1)
{
int i;
FloatDef f;
Eterm res;
Eterm* hp;
char *buf = NULL;

i = list_length(BIF_ARG_1);
if (i < 0) {
badarg:
if (buf)
erts_free(ERTS_ALC_T_TMP, (void *) buf);
BIF_ERROR(BIF_P, BADARG);
}

if (i < 0)
BIF_ERROR(BIF_P, BADARG);

buf = (char *) erts_alloc(ERTS_ALC_T_TMP, i + 1);

if (intlist_to_buf(BIF_ARG_1, buf, i) < 0)
goto badarg;
goto list_to_float_1_error;
buf[i] = '\0'; /* null terminal */

if ((res = do_charbuf_to_float(BIF_P,buf)) == THE_NON_VALUE)
goto list_to_float_1_error;

erts_free(ERTS_ALC_T_TMP, (void *) buf);
BIF_RET(res);

list_to_float_1_error:
erts_free(ERTS_ALC_T_TMP, (void *) buf);
BIF_ERROR(BIF_P, BADARG);

}

BIF_RETTYPE binary_to_float_1(BIF_ALIST_1)
{
Eterm res;
Eterm binary = BIF_ARG_1;
Sint size;
byte* bytes, *buf;
Eterm* real_bin;
Uint offs = 0;
Uint bit_offs = 0;

if (is_not_binary(binary) || (size = binary_size(binary)) == 0)
BIF_ERROR(BIF_P, BADARG);

/*
* Unfortunately we have to copy the binary because we have to insert
* the '\0' at the end of the binary for strtod to work
* (there is no nstrtod :( )
*/

buf = erts_alloc(ERTS_ALC_T_TMP, size + 1);

real_bin = binary_val(binary);
if (*real_bin == HEADER_SUB_BIN) {
ErlSubBin* sb = (ErlSubBin *) real_bin;
if (sb->bitsize) {
goto binary_to_float_1_error;
}
offs = sb->offs;
bit_offs = sb->bitoffs;
real_bin = binary_val(sb->orig);
}
if (*real_bin == HEADER_PROC_BIN) {
bytes = ((ProcBin *) real_bin)->bytes + offs;
} else {
bytes = (byte *)(&(((ErlHeapBin *) real_bin)->data)) + offs;
}
if (bit_offs)
erts_copy_bits(bytes, bit_offs, 1, buf, 0, 1, size*8);
else
memcpy(buf, bytes, size);

buf[size] = '\0';

if ((res = do_charbuf_to_float(BIF_P,(char*)buf)) == THE_NON_VALUE)
goto binary_to_float_1_error;

if (sys_chars_to_double(buf, &f.fd) != 0)
goto badarg;
hp = HAlloc(BIF_P, FLOAT_SIZE_OBJECT);
res = make_float(hp);
PUT_DOUBLE(f, hp);
erts_free(ERTS_ALC_T_TMP, (void *) buf);
BIF_RET(res);

binary_to_float_1_error:
erts_free(ERTS_ALC_T_TMP, (void *) buf);
BIF_ERROR(BIF_P, BADARG);
}

/**********************************************************************/
Expand Down
3 changes: 3 additions & 0 deletions erts/emulator/beam/bif.tab
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Original file line number Diff line number Diff line change
Expand Up @@ -565,6 +565,9 @@ bif erlang:binary_to_integer/1
bif erlang:binary_to_integer/2
bif erlang:integer_to_binary/1
bif erlang:list_to_integer/2
bif erlang:float_to_binary/1
bif erlang:float_to_binary/2
bif erlang:binary_to_float/1

#
# Obsolete
Expand Down
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