532 lines
9.3 KiB
C
532 lines
9.3 KiB
C
#include "libc/macros.h"
|
|
#include "libc/str/str.h"
|
|
#include "third_party/dtoa/dtoa.h"
|
|
|
|
/**
|
|
* @fileoverview Plan 9 strtod().
|
|
* It's like dtoa but smaller.
|
|
*/
|
|
|
|
asm(".ident\t\"\\n\\n\
|
|
Plan 9 » strtod (MIT)\\n\
|
|
The authors of this software are Rob Pike and Ken Thompson.\\n\
|
|
Copyright (c) 2002 by Lucent Technologies.\"");
|
|
asm(".include \"libc/disclaimer.inc\"");
|
|
|
|
#define nelem(a) ARRAYLEN(a)
|
|
#define ulong unsigned long
|
|
#define nil NULL
|
|
#define __NaN() __builtin_nanf("")
|
|
|
|
/* clang-format off */
|
|
/* The authors of this software are Rob Pike and Ken Thompson.
|
|
* Copyright (c) 2002 by Lucent Technologies.
|
|
* Permission to use, copy, modify, and distribute this software for any
|
|
* purpose without fee is hereby granted, provided that this entire notice
|
|
* is included in all copies of any software which is or includes a copy
|
|
* or modification of this software and in all copies of the supporting
|
|
* documentation for such software.
|
|
* THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
|
|
* WARRANTY. IN PARTICULAR, NEITHER THE AUTHORS NOR LUCENT TECHNOLOGIES MAKE ANY
|
|
* REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY
|
|
* OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
|
|
*/
|
|
|
|
#include "libc/str/str.h"
|
|
#include "libc/math.h"
|
|
#include "libc/sysv/errfuns.h"
|
|
|
|
static ulong
|
|
umuldiv(ulong a, ulong b, ulong c)
|
|
{
|
|
double d;
|
|
|
|
d = ((double)a * (double)b) / (double)c;
|
|
if(d >= 4294967295.)
|
|
d = 4294967295.;
|
|
return (ulong)d;
|
|
}
|
|
|
|
/*
|
|
* This routine will convert to arbitrary precision
|
|
* floating point entirely in multi-precision fixed.
|
|
* The answer is the closest floating point number to
|
|
* the given decimal number. Exactly half way are
|
|
* rounded ala ieee rules.
|
|
* Method is to scale input decimal between .500 and .999...
|
|
* with external power of 2, then binary search for the
|
|
* closest mantissa to this decimal number.
|
|
* Nmant is is the required precision. (53 for ieee dp)
|
|
* Nbits is the max number of bits/word. (must be <= 28)
|
|
* Prec is calculated - the number of words of fixed mantissa.
|
|
*/
|
|
enum
|
|
{
|
|
Nbits = 28, /* bits safely represented in a ulong */
|
|
Nmant = 53, /* bits of precision required */
|
|
Prec = (Nmant+Nbits+1)/Nbits, /* words of Nbits each to represent mantissa */
|
|
Sigbit = 1<<(Prec*Nbits-Nmant), /* first significant bit of Prec-th word */
|
|
Ndig = 1500,
|
|
One = (ulong)(1<<Nbits),
|
|
Half = (ulong)(One>>1),
|
|
Maxe = 310,
|
|
|
|
Fsign = 1<<0, /* found - */
|
|
Fesign = 1<<1, /* found e- */
|
|
Fdpoint = 1<<2, /* found . */
|
|
|
|
S0 = 0, /* _ _S0 +S1 #S2 .S3 */
|
|
S1, /* _+ #S2 .S3 */
|
|
S2, /* _+# #S2 .S4 eS5 */
|
|
S3, /* _+. #S4 */
|
|
S4, /* _+#.# #S4 eS5 */
|
|
S5, /* _+#.#e +S6 #S7 */
|
|
S6, /* _+#.#e+ #S7 */
|
|
S7 /* _+#.#e+# #S7 */
|
|
};
|
|
|
|
static int fpcmp(char*, ulong*);
|
|
static void frnorm(ulong*);
|
|
static void divascii(char*, int*, int*, int*);
|
|
static void mulascii(char*, int*, int*, int*);
|
|
|
|
typedef struct Tab Tab;
|
|
struct Tab
|
|
{
|
|
int bp;
|
|
int siz;
|
|
char* cmp;
|
|
};
|
|
|
|
double
|
|
plan9_strtod(const char *as, char **aas)
|
|
{
|
|
int na, ex, dp, bp, c, i, flag, state;
|
|
ulong low[Prec], hig[Prec], mid[Prec];
|
|
double d;
|
|
char *s, a[Ndig];
|
|
|
|
flag = 0; /* Fsign, Fesign, Fdpoint */
|
|
na = 0; /* number of digits of a[] */
|
|
dp = 0; /* na of decimal point */
|
|
ex = 0; /* exonent */
|
|
|
|
state = S0;
|
|
for(s=(char*)as;; s++) {
|
|
c = *s;
|
|
if(c >= '0' && c <= '9') {
|
|
switch(state) {
|
|
case S0:
|
|
case S1:
|
|
case S2:
|
|
state = S2;
|
|
break;
|
|
case S3:
|
|
case S4:
|
|
state = S4;
|
|
break;
|
|
|
|
case S5:
|
|
case S6:
|
|
case S7:
|
|
state = S7;
|
|
ex = ex*10 + (c-'0');
|
|
continue;
|
|
}
|
|
if(na == 0 && c == '0') {
|
|
dp--;
|
|
continue;
|
|
}
|
|
if(na < Ndig-50)
|
|
a[na++] = c;
|
|
continue;
|
|
}
|
|
switch(c) {
|
|
case '\t':
|
|
case '\n':
|
|
case '\v':
|
|
case '\f':
|
|
case '\r':
|
|
case ' ':
|
|
if(state == S0)
|
|
continue;
|
|
break;
|
|
case '-':
|
|
if(state == S0)
|
|
flag |= Fsign;
|
|
else
|
|
flag |= Fesign;
|
|
case '+':
|
|
if(state == S0)
|
|
state = S1;
|
|
else
|
|
if(state == S5)
|
|
state = S6;
|
|
else
|
|
break; /* syntax */
|
|
continue;
|
|
case '.':
|
|
flag |= Fdpoint;
|
|
dp = na;
|
|
if(state == S0 || state == S1) {
|
|
state = S3;
|
|
continue;
|
|
}
|
|
if(state == S2) {
|
|
state = S4;
|
|
continue;
|
|
}
|
|
break;
|
|
case 'e':
|
|
case 'E':
|
|
if(state == S2 || state == S4) {
|
|
state = S5;
|
|
continue;
|
|
}
|
|
break;
|
|
}
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* clean up return char-pointer
|
|
*/
|
|
switch(state) {
|
|
case S0:
|
|
if(strcasecmp(s, "nan") == 0) {
|
|
if(aas != nil)
|
|
*aas = s+3;
|
|
goto retnan;
|
|
}
|
|
case S1:
|
|
if(strcasecmp(s, "infinity") == 0) {
|
|
if(aas != nil)
|
|
*aas = s+8;
|
|
goto retinf;
|
|
}
|
|
if(strcasecmp(s, "inf") == 0) {
|
|
if(aas != nil)
|
|
*aas = s+3;
|
|
goto retinf;
|
|
}
|
|
case S3:
|
|
if(aas != nil)
|
|
*aas = (char*)as;
|
|
goto ret0; /* no digits found */
|
|
case S6:
|
|
s--; /* back over +- */
|
|
case S5:
|
|
s--; /* back over e */
|
|
break;
|
|
}
|
|
if(aas != nil)
|
|
*aas = s;
|
|
|
|
if(flag & Fdpoint)
|
|
while(na > 0 && a[na-1] == '0')
|
|
na--;
|
|
if(na == 0)
|
|
goto ret0; /* zero */
|
|
a[na] = 0;
|
|
if(!(flag & Fdpoint))
|
|
dp = na;
|
|
if(flag & Fesign)
|
|
ex = -ex;
|
|
dp += ex;
|
|
if(dp < -Maxe){
|
|
erange();
|
|
goto ret0; /* underflow by exp */
|
|
} else
|
|
if(dp > +Maxe)
|
|
goto retinf; /* overflow by exp */
|
|
|
|
/*
|
|
* normalize the decimal ascii number
|
|
* to range .[5-9][0-9]* e0
|
|
*/
|
|
bp = 0; /* binary exponent */
|
|
while(dp > 0)
|
|
divascii(a, &na, &dp, &bp);
|
|
while(dp < 0 || a[0] < '5')
|
|
mulascii(a, &na, &dp, &bp);
|
|
|
|
/* close approx by naïve conversion */
|
|
mid[0] = 0;
|
|
mid[1] = 1;
|
|
for(i=0; (c=a[i]) != '\0'; i++) {
|
|
mid[0] = mid[0]*10 + (c-'0');
|
|
mid[1] = mid[1]*10;
|
|
if(i >= 8)
|
|
break;
|
|
}
|
|
low[0] = umuldiv(mid[0], One, mid[1]);
|
|
hig[0] = umuldiv(mid[0]+1, One, mid[1]);
|
|
for(i=1; i<Prec; i++) {
|
|
low[i] = 0;
|
|
hig[i] = One-1;
|
|
}
|
|
|
|
/* binary search for closest mantissa */
|
|
for(;;) {
|
|
/* mid = (hig + low) / 2 */
|
|
c = 0;
|
|
for(i=0; i<Prec; i++) {
|
|
mid[i] = hig[i] + low[i];
|
|
if(c)
|
|
mid[i] += One;
|
|
c = mid[i] & 1;
|
|
mid[i] >>= 1;
|
|
}
|
|
frnorm(mid);
|
|
|
|
/* compare */
|
|
c = fpcmp(a, mid);
|
|
if(c > 0) {
|
|
c = 1;
|
|
for(i=0; i<Prec; i++)
|
|
if(low[i] != mid[i]) {
|
|
c = 0;
|
|
low[i] = mid[i];
|
|
}
|
|
if(c)
|
|
break; /* between mid and hig */
|
|
continue;
|
|
}
|
|
if(c < 0) {
|
|
for(i=0; i<Prec; i++)
|
|
hig[i] = mid[i];
|
|
continue;
|
|
}
|
|
|
|
/* only hard part is if even/odd roundings wants to go up */
|
|
c = mid[Prec-1] & (Sigbit-1);
|
|
if(c == Sigbit/2 && (mid[Prec-1]&Sigbit) == 0)
|
|
mid[Prec-1] -= c;
|
|
break; /* exactly mid */
|
|
}
|
|
|
|
/* normal rounding applies */
|
|
c = mid[Prec-1] & (Sigbit-1);
|
|
mid[Prec-1] -= c;
|
|
if(c >= Sigbit/2) {
|
|
mid[Prec-1] += Sigbit;
|
|
frnorm(mid);
|
|
}
|
|
goto out;
|
|
|
|
ret0:
|
|
return 0;
|
|
|
|
retnan:
|
|
return __NaN();
|
|
|
|
retinf:
|
|
/*
|
|
* Unix strtod requires these. Plan 9 would return Inf(0) or Inf(-1). */
|
|
erange();
|
|
if(flag & Fsign)
|
|
return -HUGE_VAL;
|
|
return HUGE_VAL;
|
|
|
|
out:
|
|
d = 0;
|
|
for(i=0; i<Prec; i++)
|
|
d = d*One + mid[i];
|
|
if(flag & Fsign)
|
|
d = -d;
|
|
d = ldexp(d, bp - Prec*Nbits);
|
|
if(d == 0){ /* underflow */
|
|
erange();
|
|
}
|
|
return d;
|
|
}
|
|
|
|
static void
|
|
frnorm(ulong *f)
|
|
{
|
|
int i, c;
|
|
|
|
c = 0;
|
|
for(i=Prec-1; i>0; i--) {
|
|
f[i] += c;
|
|
c = f[i] >> Nbits;
|
|
f[i] &= One-1;
|
|
}
|
|
f[0] += c;
|
|
}
|
|
|
|
static int
|
|
fpcmp(char *a, ulong* f)
|
|
{
|
|
ulong tf[Prec];
|
|
int i, d, c;
|
|
|
|
for(i=0; i<Prec; i++)
|
|
tf[i] = f[i];
|
|
|
|
for(;;) {
|
|
/* tf *= 10 */
|
|
for(i=0; i<Prec; i++)
|
|
tf[i] = tf[i]*10;
|
|
frnorm(tf);
|
|
d = (tf[0] >> Nbits) + '0';
|
|
tf[0] &= One-1;
|
|
|
|
/* compare next digit */
|
|
c = *a;
|
|
if(c == 0) {
|
|
if('0' < d)
|
|
return -1;
|
|
if(tf[0] != 0)
|
|
goto cont;
|
|
for(i=1; i<Prec; i++)
|
|
if(tf[i] != 0)
|
|
goto cont;
|
|
return 0;
|
|
}
|
|
if(c > d)
|
|
return +1;
|
|
if(c < d)
|
|
return -1;
|
|
a++;
|
|
cont:;
|
|
}
|
|
}
|
|
|
|
static void
|
|
divby(char *a, int *na, int b)
|
|
{
|
|
int n, c;
|
|
char *p;
|
|
|
|
p = a;
|
|
n = 0;
|
|
while(n>>b == 0) {
|
|
c = *a++;
|
|
if(c == 0) {
|
|
while(n) {
|
|
c = n*10;
|
|
if(c>>b)
|
|
break;
|
|
n = c;
|
|
}
|
|
goto xx;
|
|
}
|
|
n = n*10 + c-'0';
|
|
(*na)--;
|
|
}
|
|
for(;;) {
|
|
c = n>>b;
|
|
n -= c<<b;
|
|
*p++ = c + '0';
|
|
c = *a++;
|
|
if(c == 0)
|
|
break;
|
|
n = n*10 + c-'0';
|
|
}
|
|
(*na)++;
|
|
xx:
|
|
while(n) {
|
|
n = n*10;
|
|
c = n>>b;
|
|
n -= c<<b;
|
|
*p++ = c + '0';
|
|
(*na)++;
|
|
}
|
|
*p = 0;
|
|
}
|
|
|
|
static Tab tab1[] =
|
|
{
|
|
{ 1, 0, ""},
|
|
{ 3, 1, "7"},
|
|
{ 6, 2, "63"},
|
|
{ 9, 3, "511"},
|
|
{13, 4, "8191"},
|
|
{16, 5, "65535"},
|
|
{19, 6, "524287"},
|
|
{23, 7, "8388607"},
|
|
{26, 8, "67108863"},
|
|
{27, 9, "134217727"},
|
|
};
|
|
|
|
static void
|
|
divascii(char *a, int *na, int *dp, int *bp)
|
|
{
|
|
int b, d;
|
|
Tab *t;
|
|
|
|
d = *dp;
|
|
if(d >= (int)(nelem(tab1)))
|
|
d = (int)(nelem(tab1))-1;
|
|
t = tab1 + d;
|
|
b = t->bp;
|
|
if(memcmp(a, t->cmp, t->siz) > 0)
|
|
d--;
|
|
*dp -= d;
|
|
*bp += b;
|
|
divby(a, na, b);
|
|
}
|
|
|
|
static void
|
|
mulby(char *a, char *p, char *q, int b)
|
|
{
|
|
int n, c;
|
|
|
|
n = 0;
|
|
*p = 0;
|
|
for(;;) {
|
|
q--;
|
|
if(q < a)
|
|
break;
|
|
c = *q - '0';
|
|
c = (c<<b) + n;
|
|
n = c/10;
|
|
c -= n*10;
|
|
p--;
|
|
*p = c + '0';
|
|
}
|
|
while(n) {
|
|
c = n;
|
|
n = c/10;
|
|
c -= n*10;
|
|
p--;
|
|
*p = c + '0';
|
|
}
|
|
}
|
|
|
|
static Tab tab2[] =
|
|
{
|
|
{ 1, 1, ""}, /* dp = 0-0 */
|
|
{ 3, 3, "125"},
|
|
{ 6, 5, "15625"},
|
|
{ 9, 7, "1953125"},
|
|
{13, 10, "1220703125"},
|
|
{16, 12, "152587890625"},
|
|
{19, 14, "19073486328125"},
|
|
{23, 17, "11920928955078125"},
|
|
{26, 19, "1490116119384765625"},
|
|
{27, 19, "7450580596923828125"}, /* dp 8-9 */
|
|
};
|
|
|
|
static void
|
|
mulascii(char *a, int *na, int *dp, int *bp)
|
|
{
|
|
char *p;
|
|
int d, b;
|
|
Tab *t;
|
|
|
|
d = -*dp;
|
|
if(d >= (int)(nelem(tab2)))
|
|
d = (int)(nelem(tab2))-1;
|
|
t = tab2 + d;
|
|
b = t->bp;
|
|
if(memcmp(a, t->cmp, t->siz) < 0)
|
|
d--;
|
|
p = a + *na;
|
|
*bp -= b;
|
|
*dp += d;
|
|
*na += d;
|
|
mulby(a, p+d, p, b);
|
|
}
|