Added a method to write variable sized unsigned values. Use this method for

all sorts of things in the object files. This does not only make the object
files smaller, but does also remove several limits (strings may be longer
than 255 bytes, several counters no longer have 8 or 16 bit limits).


git-svn-id: svn://svn.cc65.org/cc65/trunk@260 b7a2c559-68d2-44c3-8de9-860c34a00d81

src/ld65/fileio.c

@@ -35,8 +35,10 @@
 
 #include <string.h>
 
-#include "../common/xmalloc.h"
+/* common */
+#include "xmalloc.h"
 
+/* ld65 */
 #include "error.h"
 #include "fileio.h"
 
@@ -117,14 +119,31 @@ void WriteVal (FILE* F, unsigned long Val, unsigned Size)
 
 
 
+void WriteVar (FILE* F, unsigned long V)
+/* Write a variable sized value to the file in special encoding */
+{
+    /* We will write the value to the file in 7 bit chunks. If the 8th bit
+     * is clear, we're done, if it is set, another chunk follows. This will
+     * allow us to encode smaller values with less bytes, at the expense of
+     * needing 5 bytes if a 32 bit value is written to file.
+     */
+    do {
+	unsigned char C = (V & 0x7F);
+	V >>= 7;
+	if (V) {
+	    C |= 0x80;
+	}
+	Write8 (F, C);
+    } while (V != 0);
+}
+
+
+
 void WriteStr (FILE* F, const char* S)
 /* Write a string to the file */
 {
     unsigned Len = strlen (S);
-    if (Len > 255) {
-       	Internal ("String too long");
-    }
-    Write8 (F, (unsigned char) Len);
+    WriteVar (F, Len);
     WriteData (F, S, Len);
 }
 
@@ -210,37 +229,43 @@ long Read32Signed (FILE* F)
 
 
 
-char* ReadStr (FILE* F, char* Str)
-/* Read a string from the file. Str must hold 256 chars at max */
+unsigned long ReadVar (FILE* F)
+/* Read a variable size value from the file */
 {
-    /* Read the length byte */
-    unsigned Len = Read8 (F);
+    /* The value was written to the file in 7 bit chunks LSB first. If there
+     * are more bytes, bit 8 is set, otherwise it is clear.
+     */
+    unsigned char C;
+    unsigned long V = 0;
+    unsigned Shift = 0;
+    do {
+	/* Read one byte */
+	C = Read8 (F);
+	/* Encode it into the target value */
+	V |= ((unsigned long)(C & 0x7F)) << Shift;
+	/* Next value */
+	Shift += 7;
+    } while (C & 0x80);
 
-    /* Read the string itself */
-    ReadData (F, Str, Len);
-
-    /* Terminate the string and return it */
-    Str [Len] = '\0';
-    return Str;
+    /* Return the value read */
+    return V;
 }
 
 
 
-char* ReadMallocedStr (FILE* F)
-/* Read a string from the file into a malloced area */
+char* ReadStr (FILE* F)
+/* Read a string from the file (the memory will be malloc'ed) */
 {
-    /* Read the length byte */
-    unsigned Len = Read8 (F);
+    /* Read the length */
+    unsigned Len = ReadVar (F);
 
-    /* Allocate memory */
-    char* Str = xmalloc (Len + 1);
-
-    /* Read the string itself */
-    ReadData (F, Str, Len);
+    /* Allocate memory and read the string itself */
+    char* S = xmalloc (Len + 1);
+    ReadData (F, S, Len);
 
     /* Terminate the string and return it */
-    Str [Len] = '\0';
-    return Str;
+    S [Len] = '\0';
+    return S;
 }
 
 
@@ -248,10 +273,10 @@ char* ReadMallocedStr (FILE* F)
 FilePos* ReadFilePos (FILE* F, FilePos* Pos)
 /* Read a file position from the file */
 {
-    /* The line number is encoded as 24 bit value to save some space */
-    Pos->Line =	Read24 (F);
-    Pos->Col  = Read8 (F);
-    Pos->Name = Read8 (F);
+    /* Read the data fields */
+    Pos->Line =	ReadVar (F);
+    Pos->Col  = ReadVar (F);
+    Pos->Name = ReadVar (F);
     return Pos;
 }
 
@@ -268,4 +293,4 @@ void* ReadData (FILE* F, void* Data, unsigned Size)
 
 
 
-		 
+