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floating point print

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SVN=126038
This commit is contained in:
Ken Thompson 2008-07-04 18:01:35 -07:00
parent b0273023f6
commit ac5a887d5d
1 changed files with 57 additions and 1 deletions
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58
src/runtime/print.c
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@ -49,7 +49,63 @@ sys·printbool(bool v)
void
sys·printfloat(float64 v)
{
sys·write(1, "printfloat", 10);
byte buf[20];
int32 e, s, i, n;
float64 h;
n = 5; // digits printed
e = 0; // exp
s = 0; // sign
if(v != 0) {
// sign
if(v < 0) {
v = -v;
s = 1;
}
// normalize
while(v >= 10) {
e++;
v /= 10;
}
while(v < 1) {
e--;
v *= 10;
}
// round
h = 5;
for(i=0; i<n; i++)
h /= 10;
v += h;
if(v >= 10) {
e++;
v /= 10;
}
}
// format +d.dddd+edd
buf[0] = '+';
if(s)
buf[0] = '-';
for(i=0; i<n; i++) {
s = v;
buf[i+2] = s+'0';
v -= s;
v *= 10.;
}
buf[1] = buf[2];
buf[2] = '.';
buf[n+2] = '+';
if(e < 0) {
e = -e;
buf[n+2] = '-';
}
buf[n+3] = 'e';
buf[n+4] = (e/10) + '0';
buf[n+5] = (e%10) + '0';
sys·write(1, buf, n+6);
}
void