string.c File Reference

#include <system.h>
#include <string.h>

Include dependency graph for string.c:

Go to the source code of this file.

Functions
int	strlen (const char *s)
	strlen returns the length of a string More...
char *	strcpy (char *s1, const char *s2)
	strcpy copies one string to another string More...
int	atoi (const char *s)
	atoi converts and ASCII string to an integer More...
int	strcmp (const char *s1, const char *s2)
	strcmp compares two strings. More...
char *	strcat (char *s1, const char *s2)
	strcat concatenates the contents of one string onto another. More...
int	isspace (const char *c)
	isspace Determines if a character is a whitespace. More...
void *	memset (void *s, int c, size_t n)
	memset Set a region of memory. More...
char *	strtok (char *s1, const char *s2)
	strtok Split string into tokens. More...
int	sprintf (char *str, int bufLength, const char *format,...)
	sprintf print with format to specified string buffer More...
int	intToS (const int *const i, char *buf, int bufLength)
	intToS converts a signed integer to string More...
char	is_conversion_specifier (char c)
	is_conversion_specifier checks to see if the character is one of the standard printf formats More...
int	isnum (const char c)
	isnum inline helper function to check if a character is represents an ascii number More...

Function Documentation

int atoi

(

const char *

s

)

atoi converts and ASCII string to an integer

Parameters

s	const char *s, character pointer to a string.

Returns

the integer value of s.

Definition at line 46 of file string.c.

Referenced by createPCB(), setDate(), setPriority(), setTime(), and sprintf().

{
    int num = 0;

    if(!s)
    {
        return 0;
    }
    while(*s==' '){ s++; }

    int isNeg = ( *s == '-');
    if(isNeg || (*s == '+')){ s++; }
    while((*s >= '0') && (*s <= '9' ))
    {
        num = (num*10) + (*s - '0');
        s++;
    }
    if(isNeg)
    {
        num = num *(-1);
    }

    return num; // return integer
}

int intToS	(	const int *const	i,
		char *	buf,
		int	bufLength
	)

intToS converts a signed integer to string

Parameters

i	integer to convert
buf	buf to place the converted string
bufLength	length of the buffer, string writing will not exceed this value

Returns

num of characters written to buffer

Definition at line 317 of file string.c.

References strlen().

Referenced by sprintf().

{
    if(!buf)
    { 
        return 0; 
    }
    
    int cpy=*i;
    int length = 1;
    if(*i < 0)
    { 
        cpy*=-1;
        length++;
    }
    
    do{
        length++;
    }while((cpy/=10)); //find total length of string
    
    if(bufLength<length+1) //if the bufLength is less than the length+null term, return 0
    {
        return 0;
    }
            
    cpy=(*i<0)?(*i) * -1: *i;      //reset val copy
    length--;
    buf[length]='\0'; //insert null terminator at end of string
    length--;
    for(; length >= 0; length--) //convert int to char and copy into buffer backwards
    {
        buf[length] = cpy%10 + '0'; 
        cpy/=10;
    }
    if(*i<0)
    {
        buf[0]='-';
    }
    
    return strlen(buf);
}

char is_conversion_specifier

(

char

c

)

is_conversion_specifier checks to see if the character is one of the standard printf formats

Parameters

c	character to check

Returns

returns the character if the character is a format specifier, else returns 0

Definition at line 363 of file string.c.

Referenced by sprintf().

{
    switch(c)
    {
        case 'c': 
        case 's': 
        case 'd': case 'i': 
        case 'u': case 'o': case 'x': case 'X': 
        case 'f': case 'F': case 'e': case 'E': case 'a': case'A': case 'g': case 'G':
        case 'p': 
            return c; 
        
        default: return 0;
    }
    return 0;
}

int isnum ( const char  c )

inline

isnum inline helper function to check if a character is represents an ascii number

Parameters

c	character to check

Returns

returns 1 if the character is an ascii number, else returns 0

Definition at line 385 of file string.c.

Referenced by sprintf().

{
   return ((c >= '0') && (c <= '9'));
}

int isspace

(

const char *

c

)

isspace Determines if a character is a whitespace.

Parameters

c	character to check.

Returns

1 if it is a whitespace, 0 if it is not a whitespace.

Definition at line 114 of file string.c.

{
  if (*c == ' '  ||
      *c == '\n' ||
      *c == '\r' ||
      *c == '\f' ||
      *c == '\t' ||
      *c == '\v'){
    return 1;
  }
  return 0;
}

void* memset	(	void *	s,
		int	c,
		size_t	n
	)

memset Set a region of memory.

Parameters

s	destination.
c	byte to write.
n	count.

Returns

void.

Definition at line 139 of file string.c.

Referenced by init_idt(), init_paging(), kmain(), and loadr3().

{
  unsigned char *p = (unsigned char *) s;
  while(n--){
    *p++ = (unsigned char) c;
  }
  return s;
}

int sprintf	(	char *	str,
		int	bufLength,
		const char *	format,
			...
	)

sprintf print with format to specified string buffer

Parameters

str	a char *, place where the built string will be placed
bufLength	the size of the buffer of the char *, string writing will not exceed this value
format	a format string confirming to the std library format
...	any number of parameters that will be printed according to the format. if wrong type is specified, behavior is undefined

Returns

the number of characters placed in the output buffer plus the null character

Definition at line 229 of file string.c.

References arg_list, atoi(), init_arg_list, intToS(), is_conversion_specifier(), isnum(), strcpy(), and strlen().

{ 

    if(!str || bufLength <= 0) {
     return 0;
    }

    arg_list list;
    init_arg_list(list, format);

    int newStrIndex = 0;
    int index, formatLength = strlen(format);
    for(index = 0; format[index] != '\0' && index <= formatLength; index++)
    {
     
     //flag is -1 until fulfilled, flag is 0 if not requested
        if(format[index] == '%')
        {
            char leftJustified=0, alwaysAppendSign=0, subSignWithSpace=0, altForm=0, padWithZeros=0;
            int minFieldWidth=0, precision=0;
            (void)padWithZeros;
            for(; !is_conversion_specifier(format[index]); index++)
            {
                if(format[index]=='\0')
                {
                    return 0; //if we reach the end of the string, exit as the format is missing
                }
                if(!minFieldWidth && !precision)
                {
                    switch(format[index])
                    {           
                        case '-': leftJustified=1; break;
                        case '+': if(!leftJustified) {alwaysAppendSign=1;} break;
                        case ' ': if(!leftJustified && !alwaysAppendSign){subSignWithSpace=1;} break;
                        case '#': if(!leftJustified && !alwaysAppendSign && !subSignWithSpace) {altForm=1;} break;
                        case '0': if(!leftJustified && !alwaysAppendSign && !subSignWithSpace && !altForm){padWithZeros=1;} break;
                    }
                }
                if(format[index] == '.'){ precision = -1;}
                if(isnum(format[index])) //implement the * modifier here
                {
                    if(precision==-1)
                    { 
                        precision = atoi(&format[index]); 
                    }
                    else if(!minFieldWidth) 
                    { 
                        minFieldWidth = atoi(&format[index]); 
                    }
                }
            }//finished parsing one conversion   
            //need to implement all modifiers
            if(format[index]=='d')
            {
                newStrIndex += intToS((int*)next_arg_in_list(&list, &format[index], 0), &str[newStrIndex], bufLength-newStrIndex);
            }
            else if(format[index]=='c')
            {
                str[newStrIndex]= **((char**)next_arg_in_list(&list, &format[index], 0));
                newStrIndex++;
            }
            else if(format[index]=='s')
            {
                char *strToCopy = *((char**)next_arg_in_list(&list, &format[index], 0));
                int lengthOfCopy = strlen(strToCopy);
                strcpy(&str[newStrIndex], strToCopy);
                newStrIndex += lengthOfCopy;
            }
        }
        else
        {
            str[newStrIndex] = format[index];
            newStrIndex++;
        }
    }
    str[newStrIndex]=0;
    return newStrIndex;
}

char* strcat	(	char *	s1,
		const char *	s2
	)

strcat concatenates the contents of one string onto another.

Parameters

s1	destination string.
s2	source string.

Returns

The combined string s1 and s2.

Definition at line 101 of file string.c.

Referenced by klogv(), and kpanic().

{
  char *rc = s1;
  if (*s1) while(*++s1);
  while( (*s1++ = *s2++) );
  return rc;
}

int strcmp	(	const char *	s1,
		const char *	s2
	)

strcmp compares two strings.

Parameters

s1	string 1 to compare.
s2	string 2 to compare.

Returns

if the two strings are equal. If they are equal it will return 0, otherwise will return a non-zero integer.

Definition at line 77 of file string.c.

Referenced by date(), exec_comm(), helpDate(), helpFunc(), helpMCB(), helpPcb(), helpTime(), isEmpty(), mcbFunc(), pcbFunc(), pcbSearchFunc(), searchcompFunction(), shutdownFunc(), stringToClass(), and time().

{

  // Remarks:
  // 1) If we made it to the end of both strings (i. e. our pointer points to a
  //    '\0' character), the function will return 0
  // 2) If we didn't make it to the end of both strings, the function will
  //    return the difference of the characters at the first index of
  //    indifference.
  int i = 0;
  for(; (s1[i]) && (s2[i]) && (s1[i]==s2[i]); i++)
  {
  }
  
  return s1[i]-s2[i];
}

char* strcpy	(	char *	s1,
		const char *	s2
	)

strcpy copies one string to another string

Parameters

s1	destination string. Character pointer to a string.
s2	source string. Character pointer to a string.

Returns

return s1.

Definition at line 26 of file string.c.

Referenced by parse_comm(), serial_poll(), setupPCB(), and sprintf().

{
    char* s1Cpy = s1;
  while(*s2 != '\0') {
      *s1 = *s2;
      s1++;
      s2++;
   }
   if(*s2 == '\0') {
      
      *s1 = *s2;
   }
  return s1Cpy; // return pointer to destination string
}

int strlen

(

const char *

s

)

strlen returns the length of a string

Parameters

s	character pointer to a string

Returns

the length of the string

Definition at line 10 of file string.c.

Referenced by helpDate(), helpTime(), intToS(), setDate(), setTime(), setupPCB(), and sprintf().

{
   int length = 0;
   while(s[length] != '\0') {
    length++;
   }
   //length++;
  return length; // return length of string
}

char* strtok	(	char *	s1,
		const char *	s2
	)

strtok Split string into tokens.

Parameters

s1	String to split
s2	Delimeter.

Returns

String split into delimeters.

Definition at line 154 of file string.c.

References NULL.

Referenced by parse_comm().

{
  static char *tok_tmp = NULL;
  const char *p = s2;

  //new string
  if (s1!=NULL){
    tok_tmp = s1;
  }
  //old string cont'd
  else {
    if (tok_tmp==NULL){
      return NULL;
    }
    s1 = tok_tmp;
  }

  //skip leading s2 characters
  while ( *p && *s1 ){
    if (*s1==*p){
      ++s1;
      p = s2;
      continue;
    }
    ++p;
  }

  //no more to parse
  if (!*s1){
    return (tok_tmp = NULL);
  }

  //skip non-s2 characters
  tok_tmp = s1;
  while (*tok_tmp){
    p = s2;
    while (*p){
      if (*tok_tmp==*p++){
    *tok_tmp++ = '\0';
    return s1;
      }
    }
    ++tok_tmp;
  }

  //end of string
  tok_tmp = NULL;
  return s1;
}