Implement DS for linker scripts (#1206)

man/rgblink.5

@@ -67,10 +67,11 @@ are only relevant to assembly code and do not apply in section names.
 When a new bank statement is found, sections found after it will be placed right from the beginning of that bank.
 If the linker script switches to a different bank and then comes back to a previous one, it will continue from the last address that was used.
 .Pp
-The only two commands are
-.Ic ORG
+The only three commands are
+.Ic ORG ,
+.Ic ALIGN ,
 and
-.Ic ALIGN :
+.Ic DS :
 .Bl -bullet
 .It
 .Ic ORG
@@ -83,6 +84,9 @@ will increase the address until it is aligned to the specified boundary
 .Ql ALIGN 8
 will align to $100
 .Pc .
+.It
+.Ic DS
+will increase the address by the specified non-negative amount.
 .El
 .Pp
 .Sy Note:

src/link/script.c

@@ -154,6 +154,7 @@ char const *tokenTypes[] = {
 enum LinkerScriptCommand {
 	COMMAND_ORG,
 	COMMAND_ALIGN,
+	COMMAND_DS,
 
 	COMMAND_INVALID
 };
@@ -170,7 +171,8 @@ struct LinkerScriptToken {
 
 static char const * const commands[] = {
 	[COMMAND_ORG] = "ORG",
-	[COMMAND_ALIGN] = "ALIGN"
+	[COMMAND_ALIGN] = "ALIGN",
+	[COMMAND_DS] = "DS"
 };
 
 static int nextChar(void)
@@ -339,10 +341,17 @@ static void processCommand(enum LinkerScriptCommand command, uint16_t arg, uint1
 		break;
 
 	case COMMAND_ALIGN:
-		if (arg >= 16)
+		if (arg >= 16) {
 			arg = 0;
-		else
-			arg = (*pc + (1 << arg) - 1) & ~((1 << arg) - 1);
+		} else {
+			uint16_t mask = (1 << arg) - 1;
+
+			arg = (*pc + mask) & ~mask;
+		}
+		break;
+
+	case COMMAND_DS:
+		arg += *pc;
 	}
 
 	if (arg < *pc)

test/link/section-attributes.asm

@@ -1,2 +1,3 @@
 SECTION "sec",ROM0,ALIGN[4]
+	ds 8, $42
 SECTION "secfix",ROM0[$20]

test/link/section-attributes.link

@@ -1,5 +1,6 @@
 ROM0
 	align 4
 	"sec"
+	ds $18
 	org $20
 	"secfix"