1 files changed, 100 insertions, 0 deletions
diff --git a/buffers.c b/buffers.c
new file mode 100644
index 0000000..5f196ea
--- /dev/null
+++ b/buffers.c
@@ -0,0 +1,100 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <strings.h>
+#include <string.h>
+#include "machine_type.h"
+#include "config.h"
+#include "buffers.h"
+
+
+
+
+// retval: OK
+// 
+tUInt32 openbuf(tBuffer* hBuf,tUInt8 bufnum,char* filename)
+{
+	hBuf->changesnum=0;
+	hBuf->valid=0;
+	hBuf->fresh=1;
+	hBuf->file=fopen(filename,"rb");
+	memcpy(hBuf->filename,filename,512);
+	hBuf->filename[511]=0;
+	if (hBuf->file)
+	{
+		hBuf->valid=1;
+		hBuf->filesize=getfilesize(hBuf->file);
+		hBuf->bufsize=hBuf->filesize;
+		hBuf->bufferpos=-1;
+		return RETOK;
+	} else return RETNOK;
+}
+
+tUInt32 readbuf(tBuffer* hBuf,tInt64 pos)
+{
+	tBool havetoread=0;
+	tInt32 bytesread;
+	if (hBuf->fresh || pos<hBuf->bufferpos || pos>(hBuf->bufferpos+BUFFERSIZE)) 
+	{
+		havetoread=1;
+		hBuf->bufferpos=pos&(~(BUFFERSIZE-1));	// floor
+	}
+	else if ((hBuf->bufferpos+BUFFERMARGIN)>pos && hBuf->bufferpos>=(BUFFERSIZE/2))
+	{
+		havetoread=1;
+		hBuf->bufferpos-=(BUFFERSIZE/2);
+	}
+	else if ((hBuf->bufferpos+BUFFERSIZE-BUFFERMARGIN)<pos && (hBuf->bufferpos+(BUFFERSIZE/2))<hBuf->bufsize && hBuf->bufsize>BUFFERSIZE)
+	{
+		havetoread=1;
+		hBuf->bufferpos+=(BUFFERSIZE/2);
+	}
+	if (havetoread)
+	{
+		hBuf->fresh=0;
+		if (hBuf->filesize>hBuf->bufferpos)
+		{
+			setfilepos(hBuf->file,hBuf->bufferpos);
+			bytesread=fread(hBuf->data,sizeof(tUInt8),BUFFERSIZE,hBuf->file);
+			if (bytesread!=BUFFERSIZE)
+			{
+				memset(&hBuf->data[bytesread],0,sizeof(tUInt8)*(BUFFERSIZE-bytesread));	// fill the rest with 0
+			}
+		} else {
+			memset(hBuf->data,0,sizeof(tUInt8)*BUFFERSIZE);
+		}
+	}
+
+	return RETOK;
+}
+
+tInt32	getbufferidx(tBuffer* hBuf,tInt64 pos)
+{
+	tInt32 retval=OK;
+	if ((pos<(hBuf->bufferpos+BUFFERMARGIN)) || (pos>(hBuf->bufferpos+BUFFERSIZE-BUFFERMARGIN)))
+	{
+		retval=readbuf(hBuf,pos);
+	}
+	if (retval==OK)
+	{
+		retval=pos-(hBuf->bufferpos);	
+	}
+	return retval;
+}
+tInt8	savechanges(tBuffer* hBuf)
+{
+	int i;
+	fclose(hBuf->file);
+	if (hBuf->changesnum)
+	{
+		hBuf->file=fopen(hBuf->filename,"r+b");
+		if (hBuf->file==NULL) return RETNOK;
+		for (i=0;i<hBuf->changesnum;i++)
+		{
+			setfilepos(hBuf->file,hBuf->changes[i].pos);
+			fwrite(&(hBuf->changes[i].after),sizeof(tUInt8),1,hBuf->file);
+		}	
+		fclose(hBuf->file);	
+	}
+	return RETOK;
+}
+