/*
* %CopyrightBegin%
*
* Copyright Ericsson AB 2002-2009. All Rights Reserved.
*
* The contents of this file are subject to the Erlang Public License,
* Version 1.1, (the "License"); you may not use this file except in
* compliance with the License. You should have received a copy of the
* Erlang Public License along with this software. If not, it can be
* retrieved online at http://www.erlang.org/.
*
* Software distributed under the License is distributed on an "AS IS"
* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
* the License for the specific language governing rights and limitations
* under the License.
*
* %CopyrightEnd%
*/
#include <string.h>
#include <stdlib.h>
#include "eidef.h"
#include "eiext.h"
#include "putget.h"
int ei_decode_big(const char *buf, int *index, erlang_big *b) {
unsigned int digit_bytes;
const unsigned char *s = (unsigned char*) buf + *index;
const unsigned char *s0 = s;
switch ( get8(s) ) {
case ERL_SMALL_BIG_EXT:
digit_bytes = get8(s);
break;
case ERL_LARGE_BIG_EXT:
digit_bytes = get32be(s);
break;
default:
return -1;
}
if ( b ) {
unsigned short *dt = b->digits;
unsigned int n = (digit_bytes+1)/2;
int i;
if ( digit_bytes != b->arity ) {
return -1;
}
b->is_neg = get8(s);
for (i = 0; i < n; ++i) {
dt[i] = s[i*2];
if ((i*2 + 1) < digit_bytes) {
dt[i] |= ((unsigned short) s[(i*2)+1]) << 8;
}
}
} else {
s++; /* skip sign byte */
}
s += digit_bytes;
*index += s-s0;
return 0;
}
erlang_big *ei_alloc_big(unsigned int digit_bytes) {
erlang_big *b;
unsigned int n = (digit_bytes+1)/2;
if ( (b = malloc(sizeof(erlang_big))) == NULL) return NULL;
memset(b,(char)0,sizeof(erlang_big));
if ( (b->digits = malloc(2*n)) == NULL) {
free(b);
return NULL;
}
b->arity = digit_bytes;
memset(b->digits,(char)0, 2*n);
return b;
}
void ei_free_big(erlang_big *b)
{
if (!b) return;
if (b->digits) free(b->digits);
free(b);
}
/* big compare functions */
typedef unsigned short Uint16;
typedef unsigned int Uint;
typedef Uint16 digit_t;
typedef Uint dsize_t;
static int I_comp(digit_t *x, dsize_t xl, digit_t *y, dsize_t yl)
{
if (xl<yl) {
return -1;
} else if (xl>yl) {
return 1;
} else {
if ( x == y ) return 0;
x += (xl-1);
y += (yl-1);
while( (xl>0) && (*x==*y) ) {
x--;
y--;
xl--;
}
if ( xl == 0 ) return 0;
return ( *x < *y ) ? -1 : 1;
}
}
int ei_big_comp(erlang_big *x, erlang_big *y)
{
if ( x->is_neg == y->is_neg ) {
int c = I_comp(x->digits,(x->arity+1)/2,y->digits,(y->arity+1)/2);
if ( x->is_neg )
return -c;
else
return c;
} else {
return x->is_neg ? -1 : 1;
}
}
#define D_EXP 16
#define D_BASE (1<<D_EXP)
#define D_DECIMAL_EXP 4 /* 10^4 == 10000 */
#define D_DECIMAL_BASE 10000 /* Max decimal exponent in a digit */
#define DLOW(x) ((digit_t)((x) & (D_BASE-1)))
#define DHIGH(x) ((digit_t)((x) >> D_EXP))
/*
* Handling of floating point exceptions.
*/
#if defined(VXWORKS) && CPU == PPC860
#undef NO_FPE_SIGNALS
#define NO_FPE_SIGNALS 1
#undef INLINED_FP_CONVERSION
#define INLINED_FP_CONVERSION 1
#endif
#ifdef USE_ISINF_ISNAN /* simulate finite() */
# define finite(f) (!isinf(f) && !isnan(f))
# define HAVE_FINITE
#endif
#ifdef NO_FPE_SIGNALS
# define ERTS_FP_CHECK_INIT() do {} while (0)
# define ERTS_FP_ERROR(f, Action) if (!finite(f)) { Action; } else {}
# define ERTS_SAVE_FP_EXCEPTION()
# define ERTS_RESTORE_FP_EXCEPTION()
#else
/* extern volatile int erl_fp_exception; */
static volatile int erl_fp_exception;
# define ERTS_FP_CHECK_INIT() do {erl_fp_exception = 0;} while (0)
# if defined(__i386__) && defined(__GNUC__)
/* extern void erts_restore_x87(void); */
static void unmask_fpe(void)
{
unsigned short cw;
__asm__ __volatile__("fstcw %0" : "=m"(cw));
cw &= ~(0x01|0x04|0x08); /* unmask IM, ZM, OM */
__asm__ __volatile__("fldcw %0" : : "m"(cw));
}
static void erts_restore_x87(void)
{
__asm__ __volatile__("fninit");
unmask_fpe();
}
static int erts_check_x87(double f)
{
__asm__ __volatile__("fwait" : "=m"(erl_fp_exception) : "m"(f));
if( !erl_fp_exception )
return 0;
erts_restore_x87();
return 1;
}
# define ERTS_FP_ERROR(f, Action) do { if( erts_check_x87((f)) ) { Action; } } while (0)
# else
# define ERTS_FP_ERROR(f, Action) if (erl_fp_exception) { Action; } else {}
# endif
# define ERTS_SAVE_FP_EXCEPTION() int old_erl_fp_exception = erl_fp_exception
# define ERTS_RESTORE_FP_EXCEPTION() \
do {erl_fp_exception = old_erl_fp_exception;} while (0)
#endif
#ifdef INLINED_FP_CONVERSION
static void join(unsigned d_split[4], unsigned *d)
{
d[0] = (d_split[0] << 31) | /* Sign bit */
((d_split[1] & 0x7FFU) << 20) | /* Exponent */
(d_split[2] & 0xFFFFFU); /* Mantissa MS bits */
d[1] = d_split[3]; /* Mantissa LS bits */
}
static int blength(unsigned long l)
{
int i;
for(i = 0; l; ++i)
l >>= 1;
return i;
}
static int bblength(erlang_big *b)
{
unsigned int wholebytes = (b->arity+1)/2;
digit_t *dp = b->digits;
while(wholebytes > 0 && dp[--wholebytes] == 0U)
;
return (wholebytes * sizeof(digit_t) * 8) + blength(dp[wholebytes]);
}
static unsigned long bindex(erlang_big *b, int ndx) {
digit_t *dp = b->digits;
int skipdigits;
int dnum;
if (ndx < 0)
return 0;
skipdigits = ndx / (sizeof(digit_t) * 8);
dnum = ndx % (sizeof(digit_t) * 8);
return !!(dp[skipdigits] & (1UL << dnum));
}
#endif
int ei_big_to_double(erlang_big *b, double *resp)
{
#ifdef INLINED_FP_CONVERSION
unsigned d_split[4];
unsigned *uresp = (unsigned *) resp;
unsigned len = bblength(b);
int i;
unsigned long msm = 0, lsm = 0;
/* OK, this is not the most efficient conversion in the world, especially
not the bit-by-bit copying to the mantissa.... Simple, working and
only for vxworks ppc860 where no sane person would use floating
point anyway, eh? /Patrik */
if (!len) {
memset(d_split,0,sizeof(d_split)); /* 0 */
} else {
--len;
if (len > 1023) { /* Infinite */
d_split[1] = 2047;
d_split[2] = d_split[3] = 0;
} else {
d_split[1] = 1023 + len;
--len; /* skip the implicit binary 1. */
for (i = 0; i < 20; ++i, --len) {
msm <<= 1;
msm |= bindex(b,len);
}
for (i = 0; i < 32; ++i, --len) {
lsm <<= 1;
lsm |= bindex(b,len);
}
d_split[2] = msm;
d_split[3] = lsm;
}
}
d_split[0] = (unsigned) !!(b->is_neg);
join(d_split,uresp);
return 0;
#else
double d = 0.0;
double d_base = 1.0;
digit_t* s = (digit_t *)b->digits;
dsize_t xl = (b->arity + 1)/2;
short xsgn = b->is_neg;
ERTS_SAVE_FP_EXCEPTION();
ERTS_FP_CHECK_INIT();
while(xl--) {
digit_t ds = *s;
double d_next = ds * d_base + d;
ERTS_FP_ERROR(d_next, ERTS_RESTORE_FP_EXCEPTION(); {fprintf(stderr,"\r\n### fp exception ###\r\n"); return -1;});
s++;
d = d_next;
d_base *= D_BASE;
}
/*
* Note: The last multiplication in the loop could trigger an exception,
* which we will ignore because the result will never be used.
*/
*resp = xsgn ? -d : d;
ERTS_FP_ERROR(*resp,;);
ERTS_RESTORE_FP_EXCEPTION();
return 0;
#endif
}
int ei_small_to_big(int s, erlang_big *b)
{
digit_t *d;
unsigned int n = (b->arity+1)/2;
if ( n < 2 ) return -1;
b->is_neg = ( s < 0 );
d = (digit_t *)b->digits;
d[0] = DLOW(s);
d[1] = DHIGH(s);
return 0;
}
