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Merge pull request #55 from DualBrain/master

Fix incorrect exponent (off by 1) for "large" values when converting …
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Cory Smith 2023-10-15 10:15:30 -05:00 committed by GitHub
commit f785c79164
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@ -6948,9 +6948,58 @@ qbs *qbs_str(float value){
qbs *qbs_str(double value){
static qbs *tqbs;
tqbs=qbs_new(32,1);
static char ch;
static int32 l,i,i2,i3,digits,exponent;
static int32 mult,exp,index;
l=sprintf((char*)&qbs_str_buffer,"% .15E",value);
// the "new version"...
// scan the result (in reverse) to determine the exponent.
exponent = 0; mult = 1;
for (i = l; i > 0; i--) {
if (!(qbs_str_buffer[i] == 0 || qbs_str_buffer[i] == 32)) { // not null or space...
if (qbs_str_buffer[i] == 43) {
break; // if a +, exit for.
} else if (qbs_str_buffer[i] == 45) {
exponent = -exponent;
break; // a -, negate exponent and exit for.
} else {
exponent += (qbs_str_buffer[i] - 48) * mult;
mult *= 10;
}
}
}
digits = 0; exp = 0;
for (i = l; i > 0; i--) {
if (exp == 0) {
if (qbs_str_buffer[i] == 69) { exp = i; } // location of the E
} else if (qbs_str_buffer[i] != 48 && qbs_str_buffer[i] != 46) {
digits = i; break;
}
}
if (digits==0){
tqbs->len=2; tqbs->chr[0]=32; tqbs->chr[1]=48; // tqbs=[space][0]
return tqbs;
}
if (exponent >= 16 || exponent <= -17) {
index=0;
for (i = 0; i < digits + 1; i++) {
ch = qbs_str_buffer[i];
tqbs->chr[index++] = ch;
}
tqbs->chr[index++] = 68;
for (i = exp + 1; i < l; i++) {
ch = qbs_str_buffer[i];
tqbs->chr[index++] = ch;
}
tqbs->len=index;
return tqbs;
}
/* ----- the "old way"; which has problems with formatting certain exponents properly.
//IMPORTANT: assumed l==23
if (l==22){memmove(&qbs_str_buffer[21],&qbs_str_buffer[20],2); qbs_str_buffer[20]=48; l=23;}
@ -6979,6 +7028,7 @@ qbs *qbs_str(double value){
if (qbs_str_buffer[19]==45) exponent=-exponent;
//OLD if ((exponent<=15)&&((exponent-digits)>=-16)) goto asdecimal;
if ((exponent<=15)&&((exponent-digits)>=-17)) goto asdecimal;
//fix up exponent to conform to QBASIC standards
//i. cull trailing 0's after decimal point (use digits to help)
//ii. cull leading 0's of exponent
@ -6997,6 +7047,8 @@ qbs *qbs_str(double value){
return tqbs;
/////////////////////
asdecimal:
*/
//calculate digits after decimal point in var. i
i=-(exponent-digits+1);
if (i<0) i=0;