reader: read and parse a BMP headers

we retrieve valuable information such as the data offset, the width and
the height of the picture which path is passed as parameter.

Signed-off-by: Olivier Gayot <duskcoder@gmail.com>

1 files changed, 103 insertions, 0 deletions

diff --git a/bmp.h b/bmp.h
new file mode 100644
index 0000000..a4d794b
--- /dev/null
+++ b/bmp.h
@@ -0,0 +1,103 @@
+/*
+ * Copyright (C) 2014 Olivier Gayot <duskcoder@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef BMP_H
+#define BMP_H
+
+#include <endian.h>
+
+#include <stdint.h>
+
+struct packed_bmp_header {
+    uint16_t magic;
+    uint32_t bmp_size;
+    uint16_t reserved;
+    uint16_t reserved2;
+    uint32_t data_offset;
+} __attribute__((packed));
+
+struct bitmap {
+    uint32_t size;
+    uint32_t data_offset;
+    uint32_t width;
+    uint32_t height;
+    uint16_t bpp;
+};
+
+/* Windows BITMAPINFOHEADER */
+struct bitmap_info_header {
+    uint32_t header_size;
+    uint32_t bmp_width;
+    uint32_t bmp_height;
+    uint16_t planes;
+    uint16_t bpp;
+    uint32_t compression;
+    uint32_t img_size;
+    uint32_t horizontal_res;
+    uint32_t vertical_res;
+    uint32_t palette;
+    uint32_t important_colors;
+} __attribute((packed));
+
+enum {
+#if __BYTE_ORDER == __BIG_ENDIAN
+    BMP_MAGIC_BM = 0x424D,
+    BMP_MAGIC_BA = 0x4241,
+    BMP_MAGIC_CI = 0x4349,
+    BMP_MAGIC_CP = 0x4350,
+    BMP_MAGIC_IC = 0x4943,
+    BMP_MAGIC_PT = 0x5054,
+#elif __BYTE_ORDER == __LITTLE_ENDIAN
+    BMP_MAGIC_BM = 0x4D42,
+    BMP_MAGIC_BA = 0x4142,
+    BMP_MAGIC_CI = 0x4943,
+    BMP_MAGIC_CP = 0x5043,
+    BMP_MAGIC_IC = 0x4349,
+    BMP_MAGIC_PT = 0x5450,
+#endif
+};
+
+enum {
+    /* bmp header */
+    BMP_ESUCCESS,
+    BMP_ENOTBMP,
+    BMP_ENOTSUPP,
+
+    BMP_EINVALSIZ,
+
+    BMP_EINVALBPP,
+
+    BMP_ERRNO_COUNT,
+};
+
+const char *bmp_error_string[] = {
+    [BMP_ESUCCESS] = "Success",
+    [BMP_ENOTBMP] = "File is not a BMP",
+    [BMP_ENOTSUPP] = "File format not supported",
+    [BMP_EINVALSIZ] = "Inconsistent file size",
+    [BMP_EINVALBPP] = "Invalid BPP value",
+};
+
+int bmp_errno = BMP_ESUCCESS;
+
+static inline const char *bmp_strerror(int err)
+{
+    return bmp_error_string[err];
+}
+
+#endif /* BMP_H */