zeOS/libc.c at master · theOfficeCat/zeOS · GitHub

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/*
 * libc.c
 */

#include <libc.h>

#include <types.h>

int errno;

void perror()
{
  write(1, "Error #: ", 7);
  char buff[16];
  itoa(errno, buff);
  write(1, buff, strlen(buff));
  write(1, "\n", 1);
}


void itoa(int a, char *b)
{
  int i, i1;
  char c;

  if (a==0) { b[0]='0'; b[1]=0; return ;}

  i=0;
  while (a>0)
  {
    b[i]=(a%10)+'0';
    a=a/10;
    i++;
  }

  for (i1=0; i1<i/2; i1++)
  {
    c=b[i1];
    b[i1]=b[i-i1-1];
    b[i-i1-1]=c;
  }
  b[i]=0;
}

int strlen(char *a)
{
  int i;

  i=0;

  while (a[i]!=0) i++;

  return i;
}

void ctox(char a, char *b)
{
  int i, i1;
  char c;

  if (a==0) { b[0]='0'; b[1]=0; return ;}

  i=0;
  while (a>0)
  {
    int num = a%16;

    if (num < 10)
      b[i]=num+'0';
    else
      b[i]=num-10+'A';

    a=a/16;
    i++;
  }

  for (i1=0; i1<i/2; i1++)
  {
    c=b[i1];
    b[i1]=b[i-i1-1];
    b[i-i1-1]=c;
  }
  b[i]=0;
}


int seed = 0;

void srand(int s)
{
  seed = s;
}

unsigned int rand()
{
  seed = (seed * 1103515245 + 12345) % 2147483648;
  return seed;
}

int atoi(char *a)
{
  int i;
  int res = 0;

  i=0;

  while (a[i]!=0 && a[i] != '\n')
  {
    res = res * 10 + a[i] - '0';
    i++;
  }

  return res;
}