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OS_Project/Part3/09_memory/libc/string.c
2023-10-18 14:04:33 -04:00

113 lines
2.4 KiB
C

#include "string.h"
/**
* K&R implementation
*/
void int_to_ascii(int n, char str[], int size) {
memory_set( (u8 *) str, 0, size);
int i, sign;
if ((sign = n) < 0) n = -n;
i = 0;
do {
str[i++] = n % 10 + '0';
} while ((n /= 10) > 0);
if (sign < 0) str[i++] = '-';
str[i] = '\0';
reverse(str);
}
// Convert the numeric value n to a character string of 0x#...# where # is hexadecimal values
// Size is the size of the char str[] array so number of hex digits is 1 less than size
// because you need a terminating 0
// the char str[] is erased with 0 values at start.
void hex_to_ascii(int n, char str[], int size) {
memory_set( (u8 *) str, 0, size);
append(str, '0');
append(str, 'x');
char zeros = 0;
s32 tmp;
int i;
for (i = 28; i > 0; i -= 4) {
tmp = (n >> i) & 0xF;
if (tmp == 0 && zeros == 0) continue;
zeros = 1;
if (tmp >= 0xA) append(str, tmp - 0xA + 'A');
else append(str, tmp + '0');
}
tmp = n & 0xF;
if (tmp >= 0xA) append(str, tmp - 0xA + 'A');
else append(str, tmp + '0');
}
/* K&R */
void reverse(char s[]) {
int c, i, j;
for (i = 0, j = strlen(s)-1; i < j; i++, j--) {
c = s[i];
s[i] = s[j];
s[j] = c;
}
}
/* K&R */
int strlen(char s[]) {
int i = 0;
while (s[i] != '\0') ++i;
return i;
}
// not K&R
int sstrlen( char s[], u32 size)
{
if( size <= 0) {
return(0);
}
u32 i = 0;
while ( (s[i] != '\0') && ( i < size)) { ++i; }
return( i);
}
void append(char s[], char n) {
int len = strlen(s);
s[len] = n;
s[len+1] = '\0';
}
void backspace(char s[]) {
int len = strlen(s);
s[len-1] = '\0';
}
/* K&R
* Returns <0 if s1<s2, 0 if s1==s2, >0 if s1>s2 */
int strcmp(char s1[], char s2[]) {
int i;
for (i = 0; s1[i] == s2[i]; i++) {
if (s1[i] == '\0') return 0;
}
return s1[i] - s2[i];
}
// Not K&R
// Compare strings for first size characters
// if size > both string sizes compare whole string
int strncmp( char s1[], char s2[], u32 size)
{
u32 i = 0;
while( (s1[i] != '\0') && (s2[i] != '\0') && (i < size) && (s1[i] == s2[i])) {
++i;
}
if(i >= size) { // match exceeded size, they are same up to size chars
return(0);
} else if ( (s1[i] == s2[i])) { // match ended before size are they same? (includeing NULL matches)
return(0);
} // else don't match return diff
return( s1[i] - s2[i]);
}