/* This software is licensed by the MIT License, see LICENSE file */
/*                                Copyright © 2022 Gregory Lirent */

#include "build.h"

int charsize(const char* s) {

    unsigned int v;
  #ifndef UNICODE_CHARSIZE_CHECK_DISABLE
    unsigned int c;
  #endif
    if (*(unsigned char*)s <= 0x7f)
        return 1;

    memcpy(&v, s, 4);

    if (IS_LITTLE_ENDIAN) {
        if ((v&0x0000c0e0) == 0x000080c0) {
  #ifndef UNICODE_CHARSIZE_CHECK_DISABLE
            if (v&0x001f) // > 0x7f
  #endif
                return 2;
        } else {

  #ifndef UNICODE_CHARSIZE_CHECK_DISABLE
            c  = (v&0x000f) << 6;
            c |= (v&0x3f00) >> 8;

            if (c >= 0x20) {
  #endif
                if ((v&0xc0c0c0f8) == 0x808080f0)
                    return 4;
                if ((v&0x00c0c0f0) == 0x008080e0)
  #ifndef UNICODE_CHARSIZE_CHECK_DISABLE
                if (c >= (0xd8<<2) && c <= (0xdf<<2)) // != (0xd800 <-> 0xdfff)
  #endif
                    return 3;
            }
  #ifndef UNICODE_CHARSIZE_CHECK_DISABLE
        }
  #endif
    } else {
        if ((v&0xe0c00000) == 0xc0800000) {
  #ifndef UNICODE_CHARSIZE_CHECK_DISABLE
            if (v&0x1f000000) // > 0x7f
  #endif
                return 2;
        } else {
  #ifndef UNICODE_CHARSIZE_CHECK_DISABLE
            c  = (v&0x0f<<24) >> 2;
            c |= (v&(0x3f<<16));

            if (c >= (0x20<<16)) {
  #endif
                if ((v&0xf8c0c0c0) == 0xf0808080)
                    return 4;
                if ((v&0xf0c0c000) == 0xe0808000)
  #ifndef UNICODE_CHARSIZE_CHECK_DISABLE
                if (c >= (0xd8<<22) && c <= (0xdf<<22)) // != (0xd800 <-> 0xdfff)
  #endif
                    return 3;
  #ifndef UNICODE_CHARSIZE_CHECK_DISABLE
            }
  #endif
        }
    }
    return 0;
}