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msvcrt: Improve string to double conversion accuracy.

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Signed-off-by: Piotr Caban <piotr@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>
This commit is contained in:
Piotr Caban 2020-04-28 19:21:57 +02:00 committed by Alexandre Julliard
parent 405c99ef52
commit ed07d07bed
2 changed files with 190 additions and 105 deletions
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278
dlls/msvcrt/string.c
View file

@ -25,6 +25,7 @@
#include "config.h"
#include "wine/port.h"
#include <assert.h>
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
@ -569,101 +570,120 @@ static double strtod16(MSVCRT_wchar_t get(void *ctx), void unget(void *ctx),
}
#endif
struct u128 {
ULONGLONG u[2];
#define LIMB_DIGITS 9 /* each DWORD stores up to 9 digits */
#define LIMB_MAX 1000000000 /* 10^9 */
#define BNUM_IDX(i) ((i) & 127)
/* bnum represents real number with fixed decimal point (after 2 limbs) */
struct bnum {
DWORD data[128]; /* circular buffer, base 10 number */
int b; /* least significant digit position */
int e; /* most significant digit position + 1 */
};
static inline struct u128 u128_lshift(struct u128 *u)
/* Returns integral part of bnum */
static inline ULONGLONG bnum_to_mant(struct bnum *b)
{
struct u128 r;
r.u[0] = u->u[0] << 1;
r.u[1] = (u->u[1] << 1) + (u->u[0] >> (sizeof(u->u[0])*8-1));
return r;
ULONGLONG ret = (ULONGLONG)b->data[BNUM_IDX(b->e-1)] * LIMB_MAX;
if(b->b != b->e-1) ret += b->data[BNUM_IDX(b->e-2)];
return ret;
}
static inline struct u128 u128_rshift(struct u128 *u)
/* Returns TRUE if new most significant limb was added */
static inline BOOL bnum_lshift(struct bnum *b, int shift)
{
struct u128 r;
DWORD rest = 0;
ULONGLONG tmp;
int i;
r.u[0] = (u->u[0] >> 1) + ((u->u[1] & 1) << (sizeof(u->u[1])*8-1));
r.u[1] = u->u[1] >> 1;
return r;
/* The limbs number can change by up to 1 so shift <= 29 */
assert(shift <= 29);
for(i=b->b; i<b->e; i++) {
tmp = ((ULONGLONG)b->data[BNUM_IDX(i)] << shift) + rest;
rest = tmp / LIMB_MAX;
b->data[BNUM_IDX(i)] = tmp % LIMB_MAX;
if(i == b->b && !b->data[BNUM_IDX(i)])
b->b++;
}
if(rest) {
b->data[BNUM_IDX(b->e)] = rest;
b->e++;
if(BNUM_IDX(b->b) == BNUM_IDX(b->e)) {
if(b->data[BNUM_IDX(b->b)]) b->data[BNUM_IDX(b->b+1)] |= 1;
b->b++;
}
return TRUE;
}
return FALSE;
}
static inline void u128_mul10(struct u128 *u)
/* Returns TRUE if most significant limb was removed */
static inline BOOL bnum_rshift(struct bnum *b, int shift)
{
struct u128 tmp;
DWORD tmp, rest = 0;
BOOL ret = FALSE;
int i;
tmp = u128_lshift(u);
*u = u128_lshift(&tmp);
*u = u128_lshift(u);
/* Compute LIMB_MAX << shift without accuracy loss */
assert(shift <= 9);
u->u[0] += tmp.u[0];
u->u[1] += tmp.u[1];
if (u->u[0] < tmp.u[0]) u->u[1]++;
}
static inline void u128_div10(struct u128 *u)
{
ULONGLONG h, l, r;
r = u->u[1] % 10;
u->u[1] /= 10;
h = (r << 32) + (u->u[0] >> 32);
r = h % 10;
h /= 10;
l = (r << 32) + (u->u[0] & 0xffffffff);
l /= 10;
u->u[0] = (h << 32) + l;
}
static double convert_e10_to_e2(int sign, int e10, ULONGLONG m, int *err)
{
int e2 = 0;
struct u128 u128;
u128.u[0] = m;
u128.u[1] = 0;
while(e10 > 0)
{
u128_mul10(&u128);
e10--;
while(u128.u[1] > MSVCRT_UI64_MAX/16)
{
u128 = u128_rshift(&u128);
e2++;
for(i=b->e-1; i>=b->b; i--) {
tmp = b->data[BNUM_IDX(i)] & ((1<<shift)-1);
b->data[BNUM_IDX(i)] = (b->data[BNUM_IDX(i)] >> shift) + rest;
rest = (LIMB_MAX >> shift) * tmp;
if(i==b->e-1 && !b->data[BNUM_IDX(i)]) {
b->e--;
ret = TRUE;
}
}
while(e10 < 0)
{
while(!(u128.u[1] & (1 << (sizeof(u128.u[1])-1))))
{
u128 = u128_lshift(&u128);
e2--;
if(rest) {
if(BNUM_IDX(b->b-1) == BNUM_IDX(b->e)) {
if(rest) b->data[BNUM_IDX(b->b)] |= 1;
} else {
b->b--;
b->data[BNUM_IDX(b->b)] = rest;
}
}
return ret;
}
u128_div10(&u128);
e10++;
static inline void bnum_mult(struct bnum *b, int mult)
{
DWORD rest = 0;
ULONGLONG tmp;
int i;
assert(mult <= LIMB_MAX);
for(i=b->b; i<b->e; i++) {
tmp = ((ULONGLONG)b->data[BNUM_IDX(i)] * mult) + rest;
rest = tmp / LIMB_MAX;
b->data[BNUM_IDX(i)] = tmp % LIMB_MAX;
if(i == b->b && !b->data[BNUM_IDX(i)])
b->b++;
}
while(u128.u[1])
{
u128 = u128_rshift(&u128);
e2++;
}
if(rest) {
b->data[BNUM_IDX(b->e)] = rest;
b->e++;
return make_double(sign, e2, u128.u[0], ROUND_DOWN, err);
if(BNUM_IDX(b->b) == BNUM_IDX(b->e)) {
if(b->data[BNUM_IDX(b->b)]) b->data[BNUM_IDX(b->b+1)] |= 1;
b->b++;
}
}
}
double parse_double(MSVCRT_wchar_t (*get)(void *ctx), void (*unget)(void *ctx),
void *ctx, MSVCRT_pthreadlocinfo locinfo, int *err)
{
static const int p10s[] = { 10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000 };
#if _MSVCR_VER >= 140
MSVCRT_wchar_t _infinity[] = { 'i', 'n', 'f', 'i', 'n', 'i', 't', 'y', 0 };
MSVCRT_wchar_t _nan[] = { 'n', 'a', 'n', 0 };
@ -671,9 +691,10 @@ double parse_double(MSVCRT_wchar_t (*get)(void *ctx), void (*unget)(void *ctx),
int matched=0;
#endif
BOOL found_digit = FALSE, found_dp = FALSE, found_sign = FALSE;
unsigned __int64 d=0, hlp;
int e2 = 0, dp=0, sign=1, off, limb_digits = 0, i;
enum round round = ROUND_ZERO;
MSVCRT_wchar_t nch;
int exp=0, sign=1;
struct bnum b;
nch = get(ctx);
if(nch == '-') {
@ -710,7 +731,7 @@ double parse_double(MSVCRT_wchar_t (*get)(void *ctx), void (*unget)(void *ctx),
unget(ctx);
}
return make_double(sign, exp, d, ROUND_ZERO, err);
return 0.0;
}
if(nch == '0') {
@ -721,19 +742,31 @@ double parse_double(MSVCRT_wchar_t (*get)(void *ctx), void (*unget)(void *ctx),
}
#endif
while(nch == '0') nch = get(ctx);
b.data[0] = 0;
b.b = 0;
b.e = 1;
while(nch>='0' && nch<='9') {
found_digit = TRUE;
hlp = d * 10 + nch - '0';
if(limb_digits == LIMB_DIGITS) {
if(BNUM_IDX(b.b-1) == BNUM_IDX(b.e)) break;
else {
b.b--;
b.data[BNUM_IDX(b.b)] = 0;
limb_digits = 0;
}
}
b.data[BNUM_IDX(b.b)] = b.data[BNUM_IDX(b.b)] * 10 + nch - '0';
limb_digits++;
nch = get(ctx);
if(d>MSVCRT_UI64_MAX/10 || hlp<d) {
exp++;
break;
} else
d = hlp;
dp++;
}
while(nch>='0' && nch<='9') {
exp++;
if(nch != '0') b.data[BNUM_IDX(b.b)] |= 1;
nch = get(ctx);
dp++;
}
if(nch == *locinfo->lconv->decimal_point) {
@ -741,17 +774,34 @@ double parse_double(MSVCRT_wchar_t (*get)(void *ctx), void (*unget)(void *ctx),
nch = get(ctx);
}
/* skip leading '0' */
if(nch=='0' && !limb_digits && !b.b) {
found_digit = TRUE;
while(nch == '0') {
nch = get(ctx);
dp--;
}
}
while(nch>='0' && nch<='9') {
found_digit = TRUE;
hlp = d * 10 + nch - '0';
if(limb_digits == LIMB_DIGITS) {
if(BNUM_IDX(b.b-1) == BNUM_IDX(b.e)) break;
else {
b.b--;
b.data[BNUM_IDX(b.b)] = 0;
limb_digits = 0;
}
}
b.data[BNUM_IDX(b.b)] = b.data[BNUM_IDX(b.b)] * 10 + nch - '0';
limb_digits++;
nch = get(ctx);
if(d>MSVCRT_UI64_MAX/10 || hlp<d)
break;
d = hlp;
exp--;
}
while(nch>='0' && nch<='9')
while(nch>='0' && nch<='9') {
if(nch != '0') b.data[BNUM_IDX(b.b)] |= 1;
nch = get(ctx);
}
if(!found_digit) {
if(nch != MSVCRT_WEOF) unget(ctx);
@ -784,9 +834,9 @@ double parse_double(MSVCRT_wchar_t (*get)(void *ctx), void (*unget)(void *ctx),
if(nch != MSVCRT_WEOF) unget(ctx);
e *= s;
if(e<0 && exp<INT_MIN-e) exp = INT_MIN;
else if(e>0 && exp>INT_MAX-e) exp = INT_MAX;
else exp += e;
if(e<0 && dp<INT_MIN-e) dp = INT_MIN;
else if(e>0 && dp>INT_MAX-e) dp = INT_MAX;
else dp += e;
} else {
if(nch != MSVCRT_WEOF) unget(ctx);
if(found_sign) unget(ctx);
@ -796,16 +846,54 @@ double parse_double(MSVCRT_wchar_t (*get)(void *ctx), void (*unget)(void *ctx),
unget(ctx);
}
if(!b.data[BNUM_IDX(b.e-1)]) return make_double(sign, 0, 0, ROUND_ZERO, err);
/* Fill last limb with 0 if needed */
if(b.b+1 != b.e) {
for(; limb_digits != LIMB_DIGITS; limb_digits++)
b.data[BNUM_IDX(b.b)] *= 10;
}
for(; BNUM_IDX(b.b) < BNUM_IDX(b.e); b.b++) {
if(b.data[BNUM_IDX(b.b)]) break;
}
/* move decimal point to limb boundry */
if(limb_digits==dp && b.b==b.e-1)
return make_double(sign, 0, b.data[BNUM_IDX(b.e-1)], ROUND_ZERO, err);
off = (dp - limb_digits) % LIMB_DIGITS;
if(off < 0) off += LIMB_DIGITS;
if(off) bnum_mult(&b, p10s[off-1]);
if(!err) err = MSVCRT__errno();
if(!d) return make_double(sign, exp, d, ROUND_ZERO, err);
if(exp > MSVCRT_DBL_MAX_10_EXP)
return make_double(sign, INT_MAX, d, ROUND_ZERO, err);
if(dp-1 > MSVCRT_DBL_MAX_10_EXP)
return make_double(sign, INT_MAX, 1, ROUND_ZERO, err);
/* Count part of exponent stored in denormalized mantissa. */
/* Increase exponent range to handle subnormals. */
if(exp < MSVCRT_DBL_MIN_10_EXP-MSVCRT_DBL_DIG-18)
return make_double(sign, INT_MIN, d, ROUND_ZERO, err);
if(dp-1 < MSVCRT_DBL_MIN_10_EXP-MSVCRT_DBL_DIG-18)
return make_double(sign, INT_MIN, 1, ROUND_ZERO, err);
return convert_e10_to_e2(sign, exp, d, err);
while(dp > 2*LIMB_DIGITS) {
if(bnum_rshift(&b, 9)) dp -= LIMB_DIGITS;
e2 += 9;
}
while(dp <= LIMB_DIGITS) {
if(bnum_lshift(&b, 29)) dp += LIMB_DIGITS;
e2 -= 29;
}
while(b.data[BNUM_IDX(b.e-1)] < LIMB_MAX/10) {
bnum_lshift(&b, 1);
e2--;
}
/* Check if fractional part is non-zero */
/* Caution: it's only correct because bnum_to_mant returns more then 53 bits */
for(i=b.e-3; i>=b.b; i--) {
if (!b.data[BNUM_IDX(b.b)]) continue;
round = ROUND_DOWN;
break;
}
return make_double(sign, e2, bnum_to_mant(&b), round, err);
}
static MSVCRT_wchar_t strtod_str_get(void *ctx)

17
dlls/ucrtbase/tests/string.c
View file

@ -77,19 +77,16 @@ static BOOL local_isnan(double d)
return d != d;
}
#define test_strtod_str(string, value, length) _test_strtod_str(__LINE__, string, value, length, FALSE)
#define test_strtod_str_todo(string, value, length) _test_strtod_str(__LINE__, string, value, length, TRUE)
static void _test_strtod_str(int line, const char* string, double value, int length, BOOL todo)
#define test_strtod_str(string, value, length) _test_strtod_str(__LINE__, string, value, length)
static void _test_strtod_str(int line, const char* string, double value, int length)
{
char *end;
double d;
d = strtod(string, &end);
todo_wine_if(todo) {
if (local_isnan(value))
ok_(__FILE__, line)(local_isnan(d), "d = %.16le (\"%s\")\n", d, string);
else
ok_(__FILE__, line)(d == value, "d = %.16le (\"%s\")\n", d, string);
}
if (local_isnan(value))
ok_(__FILE__, line)(local_isnan(d), "d = %.16le (\"%s\")\n", d, string);
else
ok_(__FILE__, line)(d == value, "d = %.16le (\"%s\")\n", d, string);
ok_(__FILE__, line)(end == string + length, "incorrect end (%d, \"%s\")\n", (int)(end - string), string);
}
@ -139,7 +136,7 @@ static void test_strtod(void)
test_strtod_str("0x1fffffffffffff.80000000000000000001", 9007199254740992.0, 37);
test_strtod_str("4.0621786324484881721115322e-53", 4.0621786324484881721115322e-53, 31);
test_strtod_str_todo("1.8905590910042396899370942", 1.8905590910042396899370942, 27);
test_strtod_str("1.8905590910042396899370942", 1.8905590910042396899370942, 27);
test_strtod_str("2.2250738585072014e-308", 2.2250738585072014e-308, 23);
test_strtod_str("4.9406564584124654e-324", 4.9406564584124654e-324, 23);
}