diff options
Diffstat (limited to 'libc/stdlib/strntoumax.c')
-rw-r--r-- | libc/stdlib/strntoumax.c | 95 |
1 files changed, 95 insertions, 0 deletions
diff --git a/libc/stdlib/strntoumax.c b/libc/stdlib/strntoumax.c new file mode 100644 index 0000000..a151ef5 --- /dev/null +++ b/libc/stdlib/strntoumax.c @@ -0,0 +1,95 @@ +/* + * Copyright (C) 2008 The Android Open Source Project + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS + * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED + * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, + * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT + * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ +#include <stddef.h> +#include <stdint.h> +#include <ctype.h> + +static inline int digitval(int ch) +{ + unsigned d; + + d = (unsigned)(ch - '0'); + if (d < 10) return (int)d; + + d = (unsigned)(ch - 'a'); + if (d < 6) return (int)(d+10); + + d = (unsigned)(ch - 'A'); + if (d < 6) return (int)(d+10); + + return -1; +} + +uintmax_t +strntoumax(const char *nptr, char **endptr, int base, size_t n) +{ + const unsigned char* p = nptr; + const unsigned char* end = p + n; + int minus = 0; + uintmax_t v = 0; + int d; + + /* skip leading space */ + while (p < end && isspace(*p)) + p++; + + /* Single optional + or - */ + if (p < end) { + char c = p[0]; + if ( c == '-' || c == '+' ) { + minus = (c == '-'); + p++; + } + } + + if ( base == 0 ) { + if ( p+2 < end && p[0] == '0' && (p[1] == 'x' || p[1] == 'X') ) { + p += 2; + base = 16; + } else if ( p+1 < end && p[0] == '0' ) { + p += 1; + base = 8; + } else { + base = 10; + } + } else if ( base == 16 ) { + if ( p+2 < end && p[0] == '0' && (p[1] == 'x' || p[1] == 'X') ) { + p += 2; + } + } + + while ( p < end && (d = digitval(*p)) >= 0 && d < base ) { + v = v*base + d; + p += 1; + } + + if ( endptr ) + *endptr = (char *)p; + + return minus ? -v : v; +} |