Loading of MSX Mode 2 pictures 256x192

src/msxformats.c

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+/* vim:expandtab:ts=2 sw=2:
+*/
+/*  Grafx2 - The Ultimate 256-color bitmap paint program
+
+    Copyright 2018-2019 Thomas Bernard
+    Copyright 2011 Pawel Góralski
+    Copyright 2009 Petter Lindquist
+    Copyright 2008 Yves Rizoud
+    Copyright 2008 Franck Charlet
+    Copyright 2007-2011 Adrien Destugues
+    Copyright 1996-2001 Sunset Design (Guillaume Dorme & Karl Maritaud)
+
+    Grafx2 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; version 2
+    of the License.
+
+    Grafx2 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 Grafx2; if not, see <http://www.gnu.org/licenses/>
+*/
+
+///@file msxformats.c
+/// Formats for the MSX machines
+
+#include <stdlib.h>
+#include <string.h>
+#include "fileformats.h"
+#include "loadsavefuncs.h"
+#include "io.h"
+#include "misc.h"
+#include "gfx2log.h"
+#include "gfx2mem.h"
+
+/**
+ * @defgroup msx MSX picture formats
+ * @ingroup loadsaveformats
+ *
+ * MODE2 : 256x192
+ * Support for the MSX pictures
+ * - SC2 "BSAVE" files
+ *
+ * @{
+ */
+
+/**
+ * Check if the file is in the MSX BSAVE format. Reads 7 bytes.
+ *
+ * @param file
+ * @param begin load address
+ * @param end end address
+ * @param exec execution address for BLOAD ,R
+ * @return 0 if the file is not in BSAVE format
+ */
+static int Check_MSX_BSAVE_format(FILE * file, word * begin, word * end, word * exec)
+{
+  byte type;
+  word b, e, r;
+  if (!Read_byte(file, &type) || !Read_word_le(file, &b) || !Read_word_le(file, &e) || !Read_word_le(file, &r))
+    return 0;
+  if (type != 0xfe)
+    return 0;
+  if (b > e)
+    return 0;
+  if (begin != NULL)
+    *begin = b;
+  if (end != NULL)
+    *end = e;
+  if (exec != NULL)
+    *exec = r;
+  return 1;
+}
+
+void Test_MSX(T_IO_Context * context, FILE * file)
+{
+  word begin, end, exec;
+  (void)context;
+  if (Check_MSX_BSAVE_format(file, &begin, &end, &exec))
+  {
+    GFX2_Log(GFX2_DEBUG, "MSX : &H%04X-&H%04X,&H%04X\n", begin, end, exec);
+    if (begin < 0x4000 && end <= 0x4000)
+      File_error = 0;
+  }
+}
+
+/**
+ * Load a MSX Screen 2 picture
+ *
+ * TMS9918 Mode II VRAM layout :
+ * - 0000-17FF : Pattern table
+ * - 1800-1AFF : Name table
+ * - 1B00-1B7F : Sprite attributes
+ * - 1B80-1FFF : UNUSED (1B80-1BAF = Palette)
+ * - 2000-37FF : Color table
+ * - 3800-3FFF : Sprite patterns
+ */
+void Load_MSX(T_IO_Context * context)
+{
+  unsigned long file_size;
+  FILE * file;
+  word begin, end, exec;
+  byte vram[16*1024];
+  int row, col, sprite;
+  word addr;
+
+  File_error = 1;
+  file = Open_file_read(context);
+  if (!Check_MSX_BSAVE_format(file, &begin, &end, &exec))
+  {
+    fclose(file);
+    return;
+  }
+  if (begin >= 0x4000 || end > 0x4000)
+  {
+    fclose(file);
+    return;
+  }
+  memset(vram, 0, sizeof(vram));
+  if (!Read_bytes(file, vram + begin, end - begin))
+  {
+    fclose(file);
+    return;
+  }
+  file_size = File_length_file(file);
+  fclose(file);
+
+  File_error = 0;
+  // TODO: load MSX palette
+  context->Transparent_color = 0; // Set color 0 as transparent
+  Pre_load(context, 256, 192, file_size, FORMAT_MSX, PIXEL_SIMPLE, 4);
+  for (row = 0; row < 24; row++)
+  {
+    for (col = 0; col < 32; col++)
+    {
+      int x, y;
+      byte pattern = vram[0x1800 + row*32 + col];
+      addr = ((row & 0x18) << 8) + (pattern << 3);
+      for (y = 0; y < 8; y++, addr++)
+      {
+        byte bits = vram[addr];
+        byte colors = vram[0x2000 + addr];
+        for (x = 0; x < 8; x++)
+        {
+          Set_pixel(context, (col << 3) + x, (row << 3) + y, bits & 0x80 ? colors >> 4 : colors & 0x0f);
+          bits <<= 1;
+        }
+      }
+    }
+  }
+  if (end <= 0x3800)
+    return;  // no sprites
+  // load sprites
+  Set_loading_layer(context, 1);
+  for (sprite = 0; sprite < 32; sprite++)
+  {
+    int x_pos, y_pos, x, y;
+    byte pattern;
+    byte color;
+
+    y_pos = vram[0x1B00 + sprite * 4];
+    x_pos = vram[0x1B00 + sprite * 4 + 1];
+    pattern = vram[0x1B00 + sprite * 4 + 2];
+    color = vram[0x1B00 + sprite * 4 + 3];
+    GFX2_Log(GFX2_DEBUG, "Sprite #%02d (%d,%d) %02X %02X\n", sprite, x_pos, y_pos, pattern, color);
+    if (y_pos == 208)
+      break;
+    y_pos = (y_pos + 1) & 0xff;
+    if (color & 0x80)
+      x_pos -= 32;
+    color &= 0x0f;
+    addr = 0x3800 + (pattern << 3);
+    // 16x16 pixels sprites
+    for (y = 0; y < 16; y++, addr++)
+    {
+      word bits = (vram[addr] << 8) | vram[addr+16];
+      for (x = 0; x < 16; x++)
+      {
+        if (bits & 0x8000)
+          Set_pixel(context, x_pos + x, y_pos + y, color);
+        bits <<= 1;
+      }
+    }
+  }
+}
+
+/* @} */