strtod, strtof, strtold

This commit is contained in:
bumbread 2022-06-06 09:02:54 +11:00
parent e18e9a988e
commit 7b6bea0ff1
3 changed files with 172 additions and 58 deletions

View File

@ -4,10 +4,10 @@
#include <stdbool.h>
#include <limits.h>
#include <errno.h>
#include <math.h>
// TODO: strto*: locale-based parsing for integers
// TODO: i made a function that parses longs and i'm fucken
// tired. someone make float parsing :kekw:
// TODO: strto*: locale-based parsing
// TODO: correctly rounded base 16 floats parsing
// Call me weak if you want but I'm actually too lazy to type
// them out every time, also they take up a lot of horiz space.
@ -36,8 +36,20 @@ static bool isbase(int c, int base) {
return val < base;
}
static bool
strprefix_i(char const *restrict str, char const *restrict prefix)
{
while(*prefix != 0) {
if(*str == 0) break;
if(toupper(*str) != toupper(*prefix)) return false;
++prefix;
++str;
}
return true;
}
// Called only when isbase(c, base) for some base in range
static long todigitl(int c) {
static long todigit(int c) {
int val;
if(isdigit(c)) {
val = c-'0';
@ -51,7 +63,7 @@ static long todigitl(int c) {
return val;
}
static intull strto_generic(
static intull strtoi_generic(
const char *restrict nptr,
char **restrict endptr,
int inbase,
@ -89,7 +101,7 @@ static intull strto_generic(
}
// See if we need to parse base in C-like format
// then set the base accordingly
if(*str == '0' && (*(str+1) == 'x' || *(str+1) == 'X')) {
if(strprefix_i(str, "0X")) {
++str;
if(base == 16 || base == 0) {
++str;
@ -109,7 +121,7 @@ static intull strto_generic(
// Parse the string of digits in the given base. If the value
// exceeds abs(int_min) we exit with range error.
while(isbase(*str, (int)base)) {
intull digit = (intull)todigitl(*str);
intull digit = (intull)todigit(*str);
if(value > (int_abs_max - digit)/base) {
goto error_out_of_range;
}
@ -152,10 +164,126 @@ finish:
return value;
}
static double strtod_generic(
const char *restrict nptr,
char **restrict endptr
) {
const char *restrict str = nptr;
bool conv_performed = false;
double value = 0.0;
double coef = 1.0;
// Skip space on the beginning
while(isspace(*str)) {
++str;
}
// Check for inf and nan
if(strprefix_i(str, "INF")) {
str += sizeof "INF"-1;
value = HUGE_VAL;
conv_performed = true;
goto finish;
}
if(strprefix_i(str, "INFINITY")) {
str += sizeof "INFINITY"-1;
value = HUGE_VAL;
conv_performed = true;
goto finish;
}
if(strprefix_i(str, "NAN")) {
str += sizeof "NAN"-1;
value = NAN;
conv_performed = true;
if(*str == '(') {
while(*str != ')') {
++str;
}
++str;
}
goto finish;
}
// Parse C float
if(*str == '+') {
++str;
}
else if(*str == '-') {
coef = -1.;
++str;
}
int base = 10;
if(strprefix_i(str, "0X")) {
str += sizeof "0X"-1;
base = 16;
}
// Parse the whole part
while(isbase(*str, base)) {
long digit = todigit(*str);
value = 10.0*value + (double)digit;
++str;
}
if(*str != '.') {
value = 0.0;
goto finish;
}
++str;
// Parse the fractional part
long exp = 1;
while(isbase(*str, base)) {
long digit = todigit(*str);
double fract = (double)digit;
long cexp = exp;
while(cexp-- != 0) {
fract /= (double)base;
}
value += fract;
++exp;
++str;
}
// Parse the exponent
if((base == 10 && strprefix_i(str, "E"))
|| (base == 16 && strprefix_i(str, "P")))
{
++str;
long exp = 0;
long exp_coef = 1;
if(*str == '+') {
++str;
}
else if(*str == '-') {
exp_coef = -1;
++str;
}
while(isdigit(*str)) {
exp = 10*exp + (long)(*str-'0');
++str;
}
if(exp_coef == 1) {
while(exp--!=0) value = value * base;
}
else if(exp_coef == -1) {
while(exp--!=0) value = value / base;
}
}
if(!isfinite(value)) {
errno = ERANGE;
value = coef*HUGE_VAL;
}
conv_performed = true;
finish:
if(endptr != NULL) {
if(conv_performed) {
*endptr = (char *)str;
}
else {
*endptr = (char *)nptr;
}
}
return coef*value;
}
intl strtol(const char *restrict nptr, char **restrict endptr, int base) {
intull int_max = (intull)LONG_MAX;
intl coef;
intull modulo = strto_generic(nptr, endptr, base, &coef, int_max);
intull modulo = strtoi_generic(nptr, endptr, base, &coef, int_max);
intl value;
if(modulo == int_max) {
value = LONG_MIN;
@ -169,7 +297,7 @@ intl strtol(const char *restrict nptr, char **restrict endptr, int base) {
intll strtoll(const char *restrict nptr, char **restrict endptr, int base) {
intull int_max = (intull)LLONG_MAX;
intl coef;
intull modulo = strto_generic(nptr, endptr, base, &coef, int_max);
intull modulo = strtoi_generic(nptr, endptr, base, &coef, int_max);
intll value;
if(modulo == int_max) {
value = LLONG_MIN;
@ -182,13 +310,13 @@ intll strtoll(const char *restrict nptr, char **restrict endptr, int base) {
intul strtoul(const char *restrict nptr, char **restrict endptr, int base) {
intull int_max = (intull)ULONG_MAX;
intull value = strto_generic(nptr, endptr, base, NULL, int_max);
intull value = strtoi_generic(nptr, endptr, base, NULL, int_max);
return (intul)value;
}
intull strtoull(const char *restrict nptr, char **restrict endptr, int base) {
intull int_max = (intull)ULLONG_MAX;
return strto_generic(nptr, endptr, base, NULL, int_max);
return strtoi_generic(nptr, endptr, base, NULL, int_max);
}
double atof(const char *nptr) {
@ -208,13 +336,13 @@ long long int atoll(const char *nptr) {
}
double strtod(const char *restrict nptr, char **restrict endptr) {
return 0;
return strtod_generic(nptr, endptr);
}
float strtof(const char *restrict nptr, char **restrict endptr) {
return 0;
return (float)strtod_generic(nptr, endptr);
}
long double strtold(const char *restrict nptr, char **restrict endptr) {
return 0;
return (long double)strtod_generic(nptr, endptr);
}

View File

@ -21,11 +21,11 @@ typedef double double_t;
#define FP_INFINITE 1
#define FP_NAN 2
FP_INFINITE
FP_NAN
FP_NORMAL
FP_SUBNORMAL
FP_ZERO
//FP_INFINITE
//FP_NAN
//FP_NORMAL
//FP_SUBNORMAL
//FP_ZERO
#define FP_FAST_FMA 1
#define FP_FAST_FMAF 1
#define FP_FAST_FMAL 1
@ -39,8 +39,11 @@ FP_ZERO
// TODO: implement this
#define fpclassify(x) 0
#define isfinite(x) 0
#define isinf(x) 0
// HACK: If its fine just remove the comment
#define isfinite(x) ((double)(x) != HUGE_VAL && (double)(x) != -HUGE_VAL)
#define isinf(x) (!(isinf(x)))
#define isnan(x) 0
#define isnormal(x) 0
#define signbit(x) 0

View File

@ -1,44 +1,27 @@
#include <assert.h>
#include <ctype.h>
#include <stdlib.h>
#include <stddef.h>
#include <stdbool.h>
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
int main(int argc, char** argv) {
const char *p = "10 200000000000000000000000000000 30 -40 junk";
// printf("Parsing '%s':\n", p);
int main(void)
{
double v0 = strtod("0X1.BC70A3D70A3D7P+6", NULL);
// parsing with error handling
const char *p = "111.11 -2.22 Nan nan(2) inF 0X1.BC70A3D70A3D7P+6 1.18973e+4932zzz";
for (;;)
{
// errno can be set to any non-zero value by a library function call
// regardless of whether there was an error, so it needs to be cleared
// in order to check the error set by strtol
errno = 0;
char *end;
const long i = strtol(p, &end, 10);
if (p == end)
break;
const bool range_error = errno == ERANGE;
// printf("Extracted '%.*s', strtol returned %ld.", (int)(end-p), p, i);
for (double f = strtod(p, &end); p != end; f = strtod(p, &end))
{
// printf("'%.*s' -> ", (int)(end-p), p);
p = end;
// if (range_error)
// printf(" Range error occurred.");
// putchar('\n');
if (errno == ERANGE){
// printf("range error, got ");
errno = 0;
}
// printf("%f\n", f);
}
// printf("Unextracted leftover: '%s'\n\n", p);
// parsing without error handling
long v1 = strtol("1010", NULL, 2);
long v2 = strtol("12", NULL, 8);
long v3 = strtol("A", NULL, 16);
long v4 = strtol("junk", NULL, 36);
long v5 = strtol("012", NULL, 0);
long v6 = strtol("0xA", NULL, 0);
long v7 = strtol("junk", NULL, 0);
return 0;
double v1 = strtod(" -0.0000000123junk", NULL);
double v2 = strtod("junk", NULL);
}