projects
/
musl
/ commitdiff
commit
grep
author
committer
pickaxe
?
search:
re
summary
|
shortlog
|
log
|
commit
| commitdiff |
tree
raw
|
patch
|
inline
| side by side (from parent 1:
470fecd
)
optimize more integer cases in floatscan; comment the whole procedure
author
Rich Felker
<dalias@aerifal.cx>
Thu, 12 Apr 2012 04:16:01 +0000
(
00:16
-0400)
committer
Rich Felker
<dalias@aerifal.cx>
Thu, 12 Apr 2012 04:16:01 +0000
(
00:16
-0400)
src/internal/floatscan.c
patch
|
blob
|
history
diff --git
a/src/internal/floatscan.c
b/src/internal/floatscan.c
index
28a09c2
..
0e1f6d0
100644
(file)
--- a/
src/internal/floatscan.c
+++ b/
src/internal/floatscan.c
@@
-59,12
+59,15
@@
static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int po
int i, j, k, a, z;
long long lrp=-1, dc=0;
long long e10=0;
int i, j, k, a, z;
long long lrp=-1, dc=0;
long long e10=0;
+ int lnz = 0;
int gotdig = 0;
int rp;
int e2;
long double y;
long double frac=0;
long double bias=0;
int gotdig = 0;
int rp;
int e2;
long double y;
long double frac=0;
long double bias=0;
+ static const int p10s[] = { 10, 100, 1000, 10000,
+ 100000, 1000000, 10000000, 100000000 };
j=0;
k=0;
j=0;
k=0;
@@
-78,6
+81,7
@@
static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int po
if (lrp!=-1) break;
lrp = dc;
} else if (k < KMAX-2) {
if (lrp!=-1) break;
lrp = dc;
} else if (k < KMAX-2) {
+ if (c!='0') lnz = dc;
dc++;
if (j) x[k] = x[k]*10 + c-'0';
else x[k] = c-'0';
dc++;
if (j) x[k] = x[k]*10 + c-'0';
else x[k] = c-'0';
@@
-114,9
+118,11
@@
static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int po
return 0;
}
return 0;
}
- if (!x[0])
- return sign * 0.0;
- if (lrp==dc && (!k || (k==1 && !j)) && (bits>30 || x[0]>>bits==0))
+ /* Handle zero specially to avoid nasty special cases later */
+ if (!x[0]) return sign * 0.0;
+
+ /* Optimize small integers (w/no exponent) and over/under-flow */
+ if (lrp==dc && dc<10 && (bits>30 || x[0]>>bits==0))
return sign * (long double)x[0];
if (lrp > -emin/2) {
errno = ERANGE;
return sign * (long double)x[0];
if (lrp > -emin/2) {
errno = ERANGE;
@@
-127,6
+133,7
@@
static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int po
return sign * LDBL_MIN * LDBL_MIN;
}
return sign * LDBL_MIN * LDBL_MIN;
}
+ /* Align incomplete final B1B digit */
if (k<KMAX && j) {
for (; j<9; j++) x[k]*=10;
k++;
if (k<KMAX && j) {
for (; j<9; j++) x[k]*=10;
k++;
@@
-138,13
+145,19
@@
static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int po
e2 = 0;
rp = lrp;
e2 = 0;
rp = lrp;
+ /* Optimize small to mid-size integers (even in exp. notation) */
+ if (lnz<9 && lnz<=rp && rp < 18) {
+ if (rp == 9) return sign * (long double)x[0];
+ if (rp < 9) return sign * (long double)x[0] / p10s[8-rp];
+ int bitlim = bits-3*(int)(rp-9);
+ if (bitlim>30 || x[0]>>bitlim==0)
+ return sign * (long double)x[0] * p10s[rp-10];
+ }
+
+ /* Align radix point to B1B digit boundary */
if (rp % 9) {
if (rp % 9) {
- static const int p10s[] = {
- 100000000, 10000000, 1000000, 100000,
- 10000, 1000, 100, 10
- };
int rpm9 = rp>=0 ? rp%9 : rp%9+9;
int rpm9 = rp>=0 ? rp%9 : rp%9+9;
- int p10 = p10s[
rpm9-1
];
+ int p10 = p10s[
8-rpm9
];
uint32_t carry = 0;
for (k=a; k!=z; k++) {
uint32_t tmp = x[k] % p10;
uint32_t carry = 0;
for (k=a; k!=z; k++) {
uint32_t tmp = x[k] % p10;
@@
-159,6
+172,7
@@
static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int po
rp += 9-rpm9;
}
rp += 9-rpm9;
}
+ /* Upscale until desired number of bits are left of radix point */
while (rp < 9*LD_B1B_DIG || (rp == 9*LD_B1B_DIG && x[a]<th[0])) {
uint32_t carry = 0;
e2 -= 29;
while (rp < 9*LD_B1B_DIG || (rp == 9*LD_B1B_DIG && x[a]<th[0])) {
uint32_t carry = 0;
e2 -= 29;
@@
-185,6
+199,7
@@
static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int po
}
}
}
}
+ /* Downscale until exactly number of bits are left of radix point */
for (;;) {
uint32_t carry = 0;
int sh = 1;
for (;;) {
uint32_t carry = 0;
int sh = 1;
@@
-218,6
+233,7
@@
static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int po
}
}
}
}
+ /* Assemble desired bits into floating point variable */
for (y=i=0; i<LD_B1B_DIG; i++) {
if ((a+i & MASK)==z) x[z=(z+1 & MASK)] = 0;
y = 1000000000.0L * y + x[a+i & MASK];
for (y=i=0; i<LD_B1B_DIG; i++) {
if ((a+i & MASK)==z) x[z=(z+1 & MASK)] = 0;
y = 1000000000.0L * y + x[a+i & MASK];
@@
-225,11
+241,13
@@
static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int po
y *= sign;
y *= sign;
+ /* Limit precision for denormal results */
if (bits > LDBL_MANT_DIG+e2-emin) {
bits = LDBL_MANT_DIG+e2-emin;
if (bits<0) bits=0;
}
if (bits > LDBL_MANT_DIG+e2-emin) {
bits = LDBL_MANT_DIG+e2-emin;
if (bits<0) bits=0;
}
+ /* Calculate bias term to force rounding, move out lower bits */
if (bits < LDBL_MANT_DIG) {
bias = copysignl(scalbn(1, 2*LDBL_MANT_DIG-bits-1), y);
frac = fmodl(y, scalbn(1, LDBL_MANT_DIG-bits));
if (bits < LDBL_MANT_DIG) {
bias = copysignl(scalbn(1, 2*LDBL_MANT_DIG-bits-1), y);
frac = fmodl(y, scalbn(1, LDBL_MANT_DIG-bits));
@@
-237,6
+255,7
@@
static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int po
y += bias;
}
y += bias;
}
+ /* Process tail of decimal input so it can affect rounding */
if ((a+i & MASK) != z) {
uint32_t t = x[a+i & MASK];
if (t < 500000000 && (t || (a+i+1 & MASK) != z))
if ((a+i & MASK) != z) {
uint32_t t = x[a+i & MASK];
if (t < 500000000 && (t || (a+i+1 & MASK) != z))