Merge pull request #552 from mattcurrie/incbin-length-optional

Make INCBIN's length argument optional

src/asm/asmy.y

@@ -1073,7 +1073,12 @@ include		: T_POP_INCLUDE string {
 ;
 
 incbin		: T_POP_INCBIN string {
-			out_BinaryFile($2);
+			out_BinaryFile($2, 0);
+			if (oFailedOnMissingInclude)
+				YYACCEPT;
+		}
+		| T_POP_INCBIN string ',' const {
+			out_BinaryFile($2, $4);
 			if (oFailedOnMissingInclude)
 				YYACCEPT;
 		}

src/asm/rgbasm.5

@@ -1080,6 +1080,8 @@ The example below includes 256 bytes from data.bin, starting from byte 78.
 .Bd -literal -offset indent
 INCBIN "data.bin",78,256
 .Ed
+.Pp
+The length argument is optional. If only the start position is specified, the bytes from the start position until the end of the file will be included.
 .Ss Unions
 .Pp
 Unions allow multiple memory allocations to overlap, like unions in C.

src/asm/section.c

@@ -583,8 +583,14 @@ void out_PCRelByte(struct Expression *expr)
 /*
  * Output a binary file
  */
-void out_BinaryFile(char const *s)
+void out_BinaryFile(char const *s, int32_t startPos)
 {
+	if (startPos < 0) {
+		yyerror("Start position cannot be negative (%" PRId32 ")",
+			startPos);
+		startPos = 0;
+	}
+
 	FILE *f = fstk_FindFile(s, NULL);
 
 	if (!f) {
@@ -602,12 +608,21 @@ void out_BinaryFile(char const *s)
 	checkcodesection();
 	if (fseek(f, 0, SEEK_END) != -1) {
 		fsize = ftell(f);
-		rewind(f);
 
-		reserveSpace(fsize);
-	} else if (errno != ESPIPE) {
-		yyerror("Error determining size of INCBIN file '%s': %s", s,
-			strerror(errno));
+		if (startPos >= fsize) {
+			yyerror("Specified start position is greater than length of file");
+			return;
+		}
+
+		fseek(f, startPos, SEEK_SET);
+		reserveSpace(fsize - startPos);
+	} else {
+		if (errno != ESPIPE)
+			yyerror("Error determining size of INCBIN file '%s': %s",
+				s, strerror(errno));
+		/* The file isn't seekable, so we'll just skip bytes */
+		while (startPos--)
+			(void)fgetc(f);
 	}
 
 	while ((byte = fgetc(f)) != EOF) {