exif-utils.c

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/* exif-utils.c
 *
 * Copyright (c) 2001 Lutz Mueller <lutz@users.sourceforge.net>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful, 
 * but WITHOUT ANY WARRANTY; without even the implied warranty of 
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details. 
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA  02110-1301  USA.
 *
 * SPDX-License-Identifier: LGPL-2.0-or-later
 */
 
#include <config.h>
 
#include <libexif/exif-utils.h>
 
void
exif_array_set_byte_order (ExifFormat f, unsigned char *b, unsigned int n,
                ExifByteOrder o_orig, ExifByteOrder o_new)
{
        unsigned int j;
        unsigned int fs = exif_format_get_size (f);
        ExifShort s;
        ExifSShort ss;
        ExifLong l;
        ExifSLong sl;
        ExifRational r;
        ExifSRational sr;
 
        if (!b || !n || !fs) return;
 
        switch (f) {
        case EXIF_FORMAT_SHORT:
                for (j = 0; j < n; j++) {
                        s = exif_get_short (b + j * fs, o_orig);
                        exif_set_short (b + j * fs, o_new, s);
                }
                break;
        case EXIF_FORMAT_SSHORT:
                for (j = 0; j < n; j++) {
                        ss = exif_get_sshort (b + j * fs, o_orig);
                        exif_set_sshort (b + j * fs, o_new, ss);
                }
                break;
        case EXIF_FORMAT_LONG:
                for (j = 0; j < n; j++) {
                        l = exif_get_long (b + j * fs, o_orig);
                        exif_set_long (b + j * fs, o_new, l);
                }
                break;
        case EXIF_FORMAT_RATIONAL:
                for (j = 0; j < n; j++) {
                        r = exif_get_rational (b + j * fs, o_orig);
                        exif_set_rational (b + j * fs, o_new, r);
                }
                break;
        case EXIF_FORMAT_SLONG:
                for (j = 0; j < n; j++) {
                        sl = exif_get_slong (b + j * fs, o_orig);
                        exif_set_slong (b + j * fs, o_new, sl);
                }
                break;
        case EXIF_FORMAT_SRATIONAL:
                for (j = 0; j < n; j++) {
                        sr = exif_get_srational (b + j * fs, o_orig);
                        exif_set_srational (b + j * fs, o_new, sr);
                }
                break;
        case EXIF_FORMAT_UNDEFINED:
        case EXIF_FORMAT_BYTE:
        case EXIF_FORMAT_ASCII:
        default:
                /* Nothing here. */
                break;
        }
}
 
ExifSShort
exif_get_sshort (const unsigned char *buf, ExifByteOrder order)
{
        if (!buf) return 0;
        switch (order) {
        case EXIF_BYTE_ORDER_MOTOROLA:
                return (((unsigned int)buf[0] << 8) | buf[1]);
        case EXIF_BYTE_ORDER_INTEL:
                return (((unsigned int)buf[1] << 8) | buf[0]);
        }
 
        /* Won't be reached */
        return (0);
}
 
ExifShort
exif_get_short (const unsigned char *buf, ExifByteOrder order)
{
        return (exif_get_sshort (buf, order) & 0xffff);
}
 
void
exif_set_sshort (unsigned char *b, ExifByteOrder order, ExifSShort value)
{
        if (!b) return;
        switch (order) {
        case EXIF_BYTE_ORDER_MOTOROLA:
                b[0] = (unsigned char) (value >> 8);
                b[1] = (unsigned char) value;
                break;
        case EXIF_BYTE_ORDER_INTEL:
                b[0] = (unsigned char) value;
                b[1] = (unsigned char) (value >> 8);
                break;
        }
}
 
void
exif_set_short (unsigned char *b, ExifByteOrder order, ExifShort value)
{
        exif_set_sshort (b, order, value);
}
 
ExifSLong
exif_get_slong (const unsigned char *b, ExifByteOrder order)
{
        if (!b) return 0;
        switch (order) {
        case EXIF_BYTE_ORDER_MOTOROLA:
                return (((uint32_t)b[0] << 24) | ((uint32_t)b[1] << 16) | ((uint32_t)b[2] << 8) | (uint32_t)b[3]);
        case EXIF_BYTE_ORDER_INTEL:
                return (((uint32_t)b[3] << 24) | ((uint32_t)b[2] << 16) | ((uint32_t)b[1] << 8) | (uint32_t)b[0]);
        }
 
        /* Won't be reached */
        return (0);
}
 
void
exif_set_slong (unsigned char *b, ExifByteOrder order, ExifSLong value)
{
        if (!b) return;
        switch (order) {
        case EXIF_BYTE_ORDER_MOTOROLA:
                b[0] = (unsigned char) (value >> 24);
                b[1] = (unsigned char) (value >> 16);
                b[2] = (unsigned char) (value >> 8);
                b[3] = (unsigned char) value;
                break;
        case EXIF_BYTE_ORDER_INTEL:
                b[3] = (unsigned char) (value >> 24);
                b[2] = (unsigned char) (value >> 16);
                b[1] = (unsigned char) (value >> 8);
                b[0] = (unsigned char) value;
                break;
        }
}
 
ExifLong
exif_get_long (const unsigned char *buf, ExifByteOrder order)
{
        return (exif_get_slong (buf, order) & 0xffffffff);
}
 
void
exif_set_long (unsigned char *b, ExifByteOrder order, ExifLong value)
{
        exif_set_slong (b, order, value);
}
 
ExifSRational
exif_get_srational (const unsigned char *buf, ExifByteOrder order)
{
        ExifSRational r;
 
        r.numerator   = buf ? exif_get_slong (buf, order) : 0;
        r.denominator = buf ? exif_get_slong (buf + 4, order) : 0;
 
        return (r);
}
 
ExifRational
exif_get_rational (const unsigned char *buf, ExifByteOrder order)
{
        ExifRational r;
 
        r.numerator   = buf ? exif_get_long (buf, order) : 0;
        r.denominator = buf ? exif_get_long (buf + 4, order) : 0;
 
        return (r);
}
 
void
exif_set_rational (unsigned char *buf, ExifByteOrder order,
                   ExifRational value)
{
        if (!buf) return;
        exif_set_long (buf, order, value.numerator);
        exif_set_long (buf + 4, order, value.denominator);
}
 
void
exif_set_srational (unsigned char *buf, ExifByteOrder order,
                    ExifSRational value)
{
        if (!buf) return;
        exif_set_slong (buf, order, value.numerator);
        exif_set_slong (buf + 4, order, value.denominator);
}
 
void
exif_convert_utf16_to_utf8 (char *out, unsigned int outlen, const unsigned char *in, unsigned int inlen)
{
        if (!outlen) {
                return;
        }
        for (;;) {
                ExifShort v;
                if (inlen < 2)
                        break;
                v = exif_get_short(in, EXIF_BYTE_ORDER_INTEL);
                if (!v)
                        break;
                if (v < 0x80) {
                        if (outlen > 1) {
                                *out++ = (char)v;
                                outlen--;
                        } else {
                                break;
                        }
                } else if (v < 0x800) {
                        if (outlen > 2) {
                                *out++ = ((v >> 6) & 0x1F) | 0xC0;
                                *out++ = (v & 0x3F) | 0x80;
                                outlen -= 2;
                        } else {
                                break;
                        }
                } else {
                        if (outlen > 3) {
                                *out++ = ((v >> 12) & 0x0F) | 0xE0;
                                *out++ = ((v >> 6) & 0x3F) | 0x80;
                                *out++ = (v & 0x3F) | 0x80;
                                outlen -= 3;
                        } else {
                                break;
                        }
                }
                in += 2;
                inlen -= 2;
        }
        *out = 0;
}