#include "byte.h"

/**
  @file   byte.c
  @author djb
  @brief  byte manipulation functions
*/

unsigned int byte_chr(char *s, unsigned int n, int c)
{
  char ch = c;
  char *t = s;

  for (;;) {
    if (!n) {
      break;
    }
    if (*t == ch) {
      break;
    }
    ++t;
    --n;
  }
  return t - s;
}

void byte_copy(void *to, unsigned int n, const void *from)
{
  char *out = to;         // share same address
  const char *in = from;  // one byte

  for (;;) {
    if (!n) {
      return;
    }
    *out++ = *in++;
    --n;
  }
}

void byte_copyr(void *to, unsigned int n, const void *from)
{
  char *out = to + n;
  const char *in = from + n;

  for (;;) {
    if (!n) {
      return;
    }
    *--out = *--in;
    --n;
  }
}

int byte_diff(const void *s, unsigned int n, const void *t)
{
  const char *a = s;
  const char *b = t;

  for (;;) {
    if (!n) {
      return 0;
    }
    if (*a != *b) {
      break;
    }
    ++a;
    ++b;
    --n;
  }
  return ((int)(unsigned int)(unsigned char)*a) - ((int)(unsigned int)(unsigned char)*b);
}

unsigned int byte_rchr(char *s, unsigned int n, int c)
{
  char ch = c;
  char *t = s;
  char *u = 0;

  for (;;) {
    if (!n) {
      break;
    }
    if (*t == ch) {
      u = t;
    }
    ++t;
    --n;
  }
  if (!u) {
    u = t;
  }
  return u - s;
}

void byte_zero(void *s, unsigned int n)
{
  char *out = s;

  for (;;) {
    if (!n) {
      break;
    }
    *out++ = 0;
    --n;
  }
}

void byte_fill(void *to, unsigned int n, int c)
{
  char *s = to;
  char ch = c;

  for (;;) {
    if (!n) {
      break;
    }
    *s++ = ch;
    --n;
  }
}