From 22619d0a64bd1792d721346650e928d7de578d35 Mon Sep 17 00:00:00 2001
From: Armin Luntzer <armin.luntzer@univie.ac.at>
Date: Wed, 6 Jun 2018 13:43:19 +0200
Subject: [PATCH] add string functions: isalpha(), isupper(), islower(),
strtol()
---
include/kernel/string.h | 5 ++
lib/string.c | 172 ++++++++++++++++++++++++++++++++++++++++
2 files changed, 177 insertions(+)
diff --git a/include/kernel/string.h b/include/kernel/string.h
index 9b4859c..b5a18ad 100644
--- a/include/kernel/string.h
+++ b/include/kernel/string.h
@@ -31,7 +31,12 @@ void bzero(void *s, size_t n);
int isdigit(int c);
int isspace(int c);
+int isalpha(int c);
+int isupper(int c);
+int islower(int c);
+
int atoi(const char *nptr);
+long int strtol(const char *nptr, char **endptr, int base);
int vprintf(const char *format, va_list ap);
diff --git a/lib/string.c b/lib/string.c
index 9ab889e..2711901 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -18,6 +18,8 @@
#include <kernel/types.h>
#include <kernel/string.h>
#include <kernel/printk.h>
+#include <kernel/log2.h>
+#include <kernel/bitops.h>
/**
@@ -486,6 +488,57 @@ int isdigit(int c)
}
EXPORT_SYMBOL(isdigit);
+
+/**
+ * @brief check if a character is from the alphabet
+ *
+ * @param c the character to test
+ *
+ * @returns 0 if not in the alphabet
+ *
+ * @note in ASCII, 'a-z' are 'A-Z' + 32
+ */
+
+int isalpha(int c)
+{
+ return ((unsigned char) c | 0x20) - 'a' < 26;
+}
+EXPORT_SYMBOL(isalpha);
+
+
+/**
+ * @brief check if an alphabetic character is in uppercase
+ *
+ * @param c the character to test
+ *
+ * @returns 0 if lowercase or out of range
+ *
+ */
+
+int isupper(int c)
+{
+ return c >= 'A' && c <= 'Z';
+}
+EXPORT_SYMBOL(isupper);
+
+
+/**
+ * @brief check if an alphabetic character is in lowercase
+ *
+ * @param c the character to test
+ *
+ * @returns 0 if uppercase or out of range
+ *
+ */
+
+int islower(int c)
+{
+ return c >= 'a' && c <= 'z';
+}
+EXPORT_SYMBOL(islower);
+
+
+
/**
* @brief convert a string to an integer
*
@@ -549,3 +602,122 @@ void *memset(void *s, int c, size_t n)
return s;
}
EXPORT_SYMBOL(memset);
+
+
+
+/**
+ * @brief convert a string to a long integer
+ *
+ * @param nptr the pointer to a string (possibly) representing a number
+ * @param endptr if not NULL, stores the pointer to the first character not part
+ * of the number
+ * @param base the base of the number string
+ *
+ * @return the converted number
+ *
+ * @note A base of 0 defaults to 10 unless the first character after
+ * ' ', '+' or '-' is a '0', which will default it to base 8, unless
+ * it is followed by 'x' or 'X' which defaults to base 16.
+ * If a number is not preceeded by a sign, it is assumed to be a unsigned
+ * type and may therefore assume the size of ULONG_MAX.
+ * If no number has been found, the function will return 0 and
+ * nptr == endptr
+ *
+ * @note if the value would over-/underflow, LONG_MAX/MIN is returned
+ */
+
+long int strtol(const char *nptr, char **endptr, int base)
+{
+ int neg = 0;
+
+ unsigned long res = 0;
+ unsigned long clamp = (unsigned long) ULONG_MAX;
+
+
+
+ if (endptr)
+ (*endptr) = (char *) nptr;
+
+ for (; isspace(*nptr); nptr++);
+
+
+ if ((*nptr) == '-') {
+ nptr++;
+ neg = 1;
+ clamp = -(unsigned long) LONG_MIN;
+ } else if ((*nptr) == '+') {
+ clamp = (unsigned long) LONG_MAX;
+ nptr++;
+ }
+
+ if (!base || base == 16) {
+ if ((*nptr) == '0') {
+ switch (nptr[1]) {
+ case 'x':
+ case 'X':
+ nptr += 2;
+ base = 16;
+ break;
+ default:
+ nptr++;
+ base = 8;
+ break;
+ }
+ } else {
+ /* default */
+ base = 10;
+ }
+ }
+
+
+ /* Now iterate over the string and add up the digits. We convert
+ * any A-Z to a-z (offset == 32 in ASCII) to check if the string
+ * contains letters representing values (A=10...Z=35). We abort if
+ * the computed digit value exceeds the given base or on overflow.
+ */
+
+ while (1) {
+ unsigned int c = (*nptr);
+ unsigned int l = c | 0x20;
+ unsigned int val;
+
+ if (isdigit(c))
+ val = c - '0';
+ else if (islower(l))
+ val = l - 'a' + 10;
+ else
+ break;
+
+ if (val >= base)
+ break;
+
+ /* Check for overflow only if result is approximately within
+ * range of it, given the base. If we overflow, set result
+ * to clamp (LONG_MAX or LONG_MIN)
+ */
+
+ if (res & (~0UL << (BITS_PER_LONG - fls(base)))) {
+ if (res > (clamp - val) / base) {
+ res = clamp;
+ break;
+ }
+ }
+
+ res = res * base + val;
+ nptr++;
+ }
+
+
+ /* update endptr if a value was found */
+ if (res)
+ if (endptr)
+ (*endptr) = (char *) nptr;
+
+
+ if (neg)
+ return - (long int) res;
+
+ return (long int) res;
+}
+
+
--
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