diff options
Diffstat (limited to 'mdk-stage1/dietlibc/lib/strtof.c')
-rw-r--r-- | mdk-stage1/dietlibc/lib/strtof.c | 66 |
1 files changed, 66 insertions, 0 deletions
diff --git a/mdk-stage1/dietlibc/lib/strtof.c b/mdk-stage1/dietlibc/lib/strtof.c new file mode 100644 index 000000000..acb081e51 --- /dev/null +++ b/mdk-stage1/dietlibc/lib/strtof.c @@ -0,0 +1,66 @@ +#include <string.h> +#include <stdlib.h> +#include <ctype.h> + +float strtof(const char* s, char** endptr) { + register const char* p = s; + register float value = 0.; + int sign = +1; + float factor; + unsigned int expo; + + while ( isspace(*p) ) + p++; + + switch (*p) { + case '-': sign = -1; + case '+': p++; + default : break; + } + + while ( (unsigned int)(*p - '0') < 10u ) + value = value*10 + (*p++ - '0'); + + if ( *p == '.' ) { + factor = 1.; + + p++; + while ( (unsigned int)(*p - '0') < 10u ) { + factor *= 0.1; + value += (*p++ - '0') * factor; + } + } + + if ( (*p | 32) == 'e' ) { + expo = 0; + factor = 10.L; + + switch (*++p) { // ja hier weiß ich nicht, was mindestens nach einem 'E' folgenden MUSS. + case '-': factor = 0.1; + case '+': p++; + break; + case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': case '8': case '9': + break; + default : value = 0.L; + p = s; + goto done; + } + + while ( (unsigned int)(*p - '0') < 10u ) + expo = 10 * expo + (*p++ - '0'); + + while ( 1 ) { + if ( expo & 1 ) + value *= factor; + if ( (expo >>= 1) == 0 ) + break; + factor *= factor; + } + } + +done: + if ( endptr != NULL ) + *endptr = (char*)p; + + return value * sign; +} |