--- joko/Uni/BSArch/04/bmp_fractal.c	2006/07/01 09:40:29	1.2
+++ joko/Uni/BSArch/04/bmp_fractal.c	2006/07/01 12:19:46	1.5
@@ -4,6 +4,10 @@
  *
  * Uebung 4.4 
  */
+
+// $Id: bmp_fractal.c,v 1.5 2006/07/01 12:19:46 joko Exp $
+
+#include <windows.h>
 #include <stdio.h>
 #include <errno.h>
 
@@ -11,6 +15,7 @@
 #define YSIZE 500
 #include "algorithm.h"
 
+
 /* BMP Header */
 unsigned char header[54]={0x42,0x4d,              // signature BM
                             0xe6,0x71,0x0b,0x0,   // filesize 750054
@@ -29,44 +34,178 @@
                             0x0,0x0,0x0,0x0       // number of important colors
                         };
 
-int main(int argc, char *argv[])
-{
-    FILE *fd;
-    int len,x,y;
-    char bgr[3];
-    short svalue;
-    int   lvalue;
-    //unsigned char header[54],*ptr=&header[0];
-      
-    fd=fopen("test.bmp","wb+");
-    if(NULL==fd)
-    {
-        perror("open"); exit(1);
-    }
 
-    len=fwrite(header,1,sizeof(header),fd); //write header
-    
-    if(-1==len || len!=sizeof(header))
-    {
-        perror("write");
-        exit(2);
+void printErrorAndExit(const char *msg, DWORD err) {
+	LPSTR lpMsgBuf;
+	if(FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER|
+			          FORMAT_MESSAGE_FROM_SYSTEM | 
+					  FORMAT_MESSAGE_IGNORE_INSERTS,
+						NULL,
+						err,
+					  MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), // Default language
+					  (LPTSTR) &lpMsgBuf,
+					  0,
+					  NULL ))
+	{
+		fprintf(stderr,"%s : %s\n",msg,lpMsgBuf);
+		LocalFree(lpMsgBuf);
+	}
+	else
+	{
+		fprintf(stderr,"Error at FormatMesage: %d\n",err=GetLastError());
+	}
+	exit(err);
+}
+
+
+void write_blank_file(char *filename) {
+
+  FILE *fd;
+  int len, i, img_size;
+
+  // open file handle
+  fd = fopen(filename, "wb+");
+  if (NULL == fd) {
+    perror("open");
+    exit(1);
+  }
+
+  // write bmp header to file
+  len = fwrite(header, 1, sizeof(header), fd);
+  
+  // error checking
+  if (-1 == len || len != sizeof(header)) {
+    perror("write");
+    exit(2);
+  }
+  
+  // write three null-bytes for each pixel to file to create a black picture
+  img_size = XSIZE * YSIZE;
+  for (i = 0; i < img_size; i++) {
+    len = fwrite("\0\0\0", 1, 3, fd);
+    if (-1 == len || len != 3) {
+      perror("write");
+      exit(4);
     }
+  }
+  
+  // close file handle
+  fclose(fd);
+}
+
+
+int main(int argc, char *argv[]) {
+
+  // MMF support
+  DWORD err;
+  HANDLE hMap, hFile;
+  LPVOID pData;
+  unsigned char *pDataBitmap, *pDataBitmapCurrent;
+
+  // workers
+  unsigned int workers = 3;
+  unsigned int worker_index, worker_rows, worker_startrow;
+  
+  // fractal calculation
+  int x, y;
+  char bgr[3];
+  
+  
+  // create empty bmp-file (black background)
+  write_blank_file("test.bmp");
+
+  /* open file for reading and writing */
+  hFile = CreateFile("test.bmp", GENERIC_WRITE|GENERIC_READ, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
+  if (INVALID_HANDLE_VALUE == hFile) {
+    err = GetLastError();
+    printErrorAndExit("Error at CreateFile",err);
+  }
+
+  /* create the file mapping object */
+  hMap = CreateFileMapping(hFile, NULL, PAGE_READWRITE, 0, 0, NULL);
+  if (NULL == hMap) {
+    printErrorAndExit("Error at CreateFileMapping", GetLastError());
+  }
+  
+  /* map the whole file into the process context */
+  pData = MapViewOfFile(hMap, FILE_MAP_WRITE, 0, 0, 0);
+  if (NULL == pData) {
+    printErrorAndExit("Error at MapViewOfFile", GetLastError());
+  }
+
+  
+  // calculate pointer to beginning of bitmap
+  pDataBitmap = (unsigned char *)((INT_PTR)pData + sizeof(header));
+  
+  // debugging
+  printf("pos. of file: %p\n", pData);
+  printf("pos. of bitmap: %p\n", pDataBitmap);
+
+  // pointer to current pixel
+  pDataBitmapCurrent = pDataBitmap;
+
+  /*
+  // turn bitmap into white wand
+  for (offset = 0; offset < 500 * 500 * 3; offset++) {
+    //pDataBitmap[offset] = 255;
+    *pDataBitmapCurrent = 255;
+    pDataBitmapCurrent++;
+  }
+  */
+
+  // calculate segments of bitmap for worker threads/processes
+  worker_rows = YSIZE / workers;
+  printf("rows for each worker: %i\n", worker_rows);
+  for (worker_index = 0; worker_index < workers; worker_index++) {
     
-    for(y=YSIZE-1;y>=0;y--)
-    {
-            for(x=0;x<XSIZE;x++)
-            {
-                getColorValuesAt(x * (2.0 / XSIZE) - 1.5, y * (2.0 / YSIZE) - 1.0,&bgr[2],&bgr[1],&bgr[0]); 
-                
-                len=fwrite(bgr,1,3,fd);
-                if(-1==len || len!=3)
-                {
-                    perror("write");
-                    exit(4);
-                }
-            }
-            /*no padding required because 1500%4 =0*/
-    }        
-    fclose(fd);
+    // number of row to start for each worker
+    worker_startrow = worker_index * worker_rows;
     
+    // recalculate number of rows for last worker if (YSIZE mod workers) != 0
+    if (worker_index == workers - 1) {
+      worker_rows = YSIZE - worker_startrow;
+      printf("rows for last worker: %i\n", worker_rows);
+    }
+  }
+
+  // calculate fractal
+  for (y=YSIZE-1; y>=0; y--) {
+          for (x=0; x<XSIZE; x++) {
+            getColorValuesAt(x * (2.0 / XSIZE) - 1.5, y * (2.0 / YSIZE) - 1.0, &bgr[2], &bgr[1], &bgr[0]); 
+            
+            // debugging
+            //printf("pointer: %p\n", pDataBitmapCurrent);
+            
+            // transfer color values to current pixel
+            pDataBitmapCurrent[0] = bgr[0];
+            pDataBitmapCurrent[1] = bgr[1];
+            pDataBitmapCurrent[2] = bgr[2];
+            
+            // move pointer to next pixel
+            pDataBitmapCurrent += 3;
+            
+          }
+          //no padding required because 1500%4 =0
+  }
+
+  
+  /* write the result into the file */
+  if (!FlushViewOfFile(pData, 0)) {
+    err = GetLastError();
+    printErrorAndExit("Error at UnmapViewOfFile", err);
+  }
+
+  /* remove the mapped file */
+  if (!UnmapViewOfFile(pData)) {
+    err = GetLastError();
+    printErrorAndExit("Error at UnmapViewOfFile", err);
+    exit(err);
+  }
+  
+  /* cleanup handles */
+  if (!CloseHandle(hMap) || !CloseHandle(hFile) ) {
+    err = GetLastError();
+    printErrorAndExit("Error at CloseHandle", err);
+  }
+
 }