#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 (;;) {
    // clang-format off
    if (!n) { break; } if (*t == ch) { break; } ++t; --n;
    if (!n) { break; } if (*t == ch) { break; } ++t; --n;
    if (!n) { break; } if (*t == ch) { break; } ++t; --n;
    if (!n) { break; } if (*t == ch) { break; } ++t; --n;
    // clang-format on
  }
  return t - s;
}

void byte_copy(void *a, unsigned int n, const void *b)
{
  char *to = a;
  const char *from = b;

  for (;;) {
    // clang-format off
    if (!n) { return; } *to++ = *from++; --n;
    if (!n) { return; } *to++ = *from++; --n;
    if (!n) { return; } *to++ = *from++; --n;
    if (!n) { return; } *to++ = *from++; --n;
    // clang-format on
  }
}

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

  for (;;) {
    // clang-format off
    if (!n) { return; } *--to = *--from; --n;
    if (!n) { return; } *--to = *--from; --n;
    if (!n) { return; } *--to = *--from; --n;
    if (!n) { return; } *--to = *--from; --n;
    // clang-format on
  }
}

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

  for (;;) {
    // clang-format off
    if (!n) { return 0; } if (*s != *t) { break; } ++s; ++t; --n;
    if (!n) { return 0; } if (*s != *t) { break; } ++s; ++t; --n;
    if (!n) { return 0; } if (*s != *t) { break; } ++s; ++t; --n;
    if (!n) { return 0; } if (*s != *t) { break; } ++s; ++t; --n;
    // clang-format on
  }
  return ((int)(unsigned int)(unsigned char)*s) - ((int)(unsigned int)(unsigned char)*t);
}

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

  for (;;) {
    // clang-format off
    if (!n) { break; } if (*t == ch) { u = t; } ++t; --n;
    if (!n) { break; } if (*t == ch) { u = t; } ++t; --n;
    if (!n) { break; } if (*t == ch) { u = t; } ++t; --n;
    if (!n) { break; } if (*t == ch) { u = t; } ++t; --n;
    // clang-format on
  }
  if (!u) u = t;
  return u - s;
}

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

  for (;;) {
    // clang-format off
    if (!n) { break; } *s++ = 0; --n;
    if (!n) { break; } *s++ = 0; --n;
    if (!n) { break; } *s++ = 0; --n;
    if (!n) { break; } *s++ = 0; --n;
    // clang-format on
  }
}

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

  for (;;) {
    // clang-format off
    if (!n) { break; } *s++ = ch; --n;
    if (!n) { break; } *s++ = ch; --n;
    if (!n) { break; } *s++ = ch; --n;
    if (!n) { break; } *s++ = ch; --n;
    // clang-format on
  }
}