Skeleton in place.

1 files changed, 263 insertions, 0 deletions

diff --git a/png8.c b/png8.c
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+++ b/png8.c
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+/*
+
+    png8 - Simple PNG sprite strip converter for assembly targets
+
+    Copyright (C) 2016  Ian Cowburn <ianc@noddybox.co.uk>
+
+    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 3 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, see <http://www.gnu.org/licenses/>.
+
+    -------------------------------------------------------------------------
+
+    Main
+
+*/
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdarg.h>
+#include <time.h>
+#include <setjmp.h>
+
+#include <png.h>
+
+/* ---------------------------------------- MACROS
+*/
+#ifndef TRUE
+#define TRUE    (1)
+#endif
+
+#ifndef FALSE
+#define FALSE   (0)
+#endif
+
+#define IS_BLACK(ul)    (((ul) && 0x00FFFFFFul) == 0)
+#define IS_TRANS(ul)    (((ul) && 0xFF000000ul) == 0)
+
+
+/* ---------------------------------------- VERSION INFO
+*/
+
+static const char *png8_usage =
+"Version 1.0 development\n"
+"\n"
+"This program is distributed in the hope that it will be useful,\n"
+"but WITHOUT ANY WARRANTY; without even the implied warranty of\n"
+"MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the\n"
+"GNU General Public License (Version 3) for more details.\n"
+"\n"
+"usage: png8 <options> <file>   -- convert a file\n"
+"usage: png8 -h                 -- get help on <options>\n";
+
+
+/* ---------------------------------------- TYPES
+*/
+typedef enum
+{
+    OUTPUT_Undefined,
+    OUTPUT_Mono,
+    OUTPUT_4Col
+} output_type_t;
+
+typedef unsigned long   ulong;
+
+
+/* ---------------------------------------- HELP & USAGE
+*/
+static void Usage(void)
+{
+    fprintf(stderr,"%s\n", png8_usage);
+    exit(EXIT_FAILURE);
+}
+
+
+static void Help(void)
+{
+    static const char *help =
+"Usage:\n"
+"           png8 <switches> <PNG file>\n"
+"\nGeneral switches:\n"
+"-h         - This help text.\n"
+"\nOne of these switches must be provided:\n"
+"-1         - Produce a monochrome sprite data set (e.g. Spectrum).\n"
+"-4         - Produce a 4-colour sprite data set (e.g. Commodore 64).\n"
+"\nOptional switches:\n"
+"-s         - Treat black the same as a transparent pixel.\n"
+"-p <text>  - Use <text> in place of 'byte' for output.\n"
+"-i         - For monochrome data, produce pre-shifted values.\n"
+"";
+
+    fprintf(stderr,"%s\n", help);
+    exit(EXIT_SUCCESS);
+}
+
+
+/* ---------------------------------------- UTIL
+*/
+static void Exit(const char *fmt, ...)
+{
+    va_list va;
+
+    va_start(va, fmt);
+    vfprintf(stderr, fmt, va);
+    va_end(va);
+
+    exit(EXIT_FAILURE);
+}
+
+
+static void *Malloc(size_t size)
+{
+    void *p = malloc(size);
+
+    if (!p)
+    {
+        Exit("memory allocation failed\n");
+    }
+
+    return p;
+}
+
+
+static ulong RGBA(png_byte r, png_byte g, png_byte b, png_byte a)
+{
+    return ((ulong)r << 16ul) |
+           ((ulong)g << 8ul) |
+           ((ulong)b) |
+           ((ulong)a << 24ul);
+}
+
+
+/* ---------------------------------------- MAIN
+*/
+int main(int argc, char *argv[])
+{
+    png_structp png;
+    png_infop png_info;
+    int num_passes;
+    png_bytep *data;
+    int width, height;
+    png_byte colour_type, colour_depth;
+    const char *opcode = "byte";
+    output_type_t output = OUTPUT_Undefined;
+    int pre_shift = FALSE;
+    int f;
+    FILE *fp;
+    char header[8];
+
+    f = 1;
+
+    while(argv[f] && argv[f][0] == '-')
+    {
+        switch(argv[f][1])
+        {
+            case 'h':
+                Help();
+                break;
+
+            case '1':
+                output = OUTPUT_Mono;
+                break;
+
+            case '4':
+                output = OUTPUT_4Col;
+                break;
+
+            default:
+                Usage();
+                break;
+        }
+
+        f++;
+    }
+
+    if (output == OUTPUT_Undefined || !argv[f])
+    {
+        Usage();
+    }
+
+    if (!(fp = fopen(argv[f], "rb")))
+    {
+        Exit("Failed to open %s\n", argv[f]);
+    }
+
+    fread(header, 1, sizeof header, fp);
+
+    if (png_sig_cmp(header, 0, sizeof header))
+    {
+        Exit("%s not recognised as a PNG file\n", argv[f]);
+    }
+
+    if (!(png = png_create_read_struct
+                                (PNG_LIBPNG_VER_STRING, NULL, NULL, NULL)))
+    {
+        Exit("png_create_read_struct failed\n");
+    }
+
+    if (!(png_info = png_create_info_struct(png)))
+    {
+        Exit("png_create_info_struct failed\n");
+    }
+
+    if (setjmp(png_jmpbuf(png)))
+    {
+        Exit("png_init_io failed\n");
+    }
+
+    png_init_io(png, fp);
+    png_set_sig_bytes(png, sizeof header);
+    png_read_info(png, png_info);
+
+    width = png_get_image_width(png, png_info);
+    height = png_get_image_height(png, png_info);
+    colour_type = png_get_color_type(png, png_info);
+    colour_depth = png_get_bit_depth(png, png_info);
+    num_passes = png_set_interlace_handling(png);
+
+    if (colour_type != PNG_COLOR_TYPE_RGBA)
+    {
+        Exit("PNG must be an RGB image with an alpha channel.\n");
+    }
+
+    png_read_update_info(png, png_info);
+
+    data = Malloc((sizeof *data) * height);
+
+    for(f = 0; f < height; f++)
+    {
+        data[f] = Malloc(png_get_rowbytes(png, png_info));
+    }
+
+    if (setjmp(png_jmpbuf(png)))
+    {
+        Exit("png_read_image failed\n");
+    }
+
+    png_read_image(png, data);
+
+    fclose(fp);
+
+    for(f = 0; f < height; f++)
+    {
+        free(data[f]);
+    }
+
+    free(data);
+
+    return EXIT_SUCCESS;
+}
+
+
+/*
+vim: ai sw=4 ts=8 expandtab
+*/