Linker scripts can aling to offsets, and require valid alignments

gbdev · Dec 11, 2023 · 48304c4 · 48304c4
1 parent fd78a9a
commit 48304c4
Show file tree

Hide file tree

Showing 5 changed files with 35 additions and 13 deletions.
diff --git a/man/rgblink.5 b/man/rgblink.5
@@ -68,15 +68,25 @@ and
 .Ic DS :
 .Bl -bullet
 .It
-.Ic ORG
-sets the address in which new sections will be placed.
+.Ic ORG Ar addr
+sets the address in which new sections will be placed to
+.Ar addr .
 It can not be lower than the current address.
 .It
-.Ic ALIGN
+.Ic ALIGN Ar addr
+or
+.Ic ALIGN Ar addr , Ar offset
 will increase the address until it is aligned to the specified boundary
-.Po it tries to set to 0 the number of bits specified after the directive:
+.Po it tries to set to
+.Ar offset
+the number of bits specified by
+.Ar align :
+for example,
 .Ql ALIGN 8
-will align to $100
+will align to $100 ,
+and
+.Ql ALIGN 8 , 10
+will align to $10A
 .Pc .
 .It
 .Ic DS

diff --git a/src/link/script.y b/src/link/script.y
@@ -49,6 +49,7 @@
 
 %token YYEOF 0 "end of file"
 %token newline
+%token COMMA ","
 %token ORG "ORG"
        INCLUDE "INCLUDE"
        ALIGN "ALIGN"
@@ -81,6 +82,7 @@ directive: section_type { setSectionType($1); }
          | section_type number { setSectionType($1, $2); }
          | ORG number { setAddr($2); }
          | ALIGN number { alignTo($2, 0); }
+         | ALIGN number COMMA number { alignTo($2, $4); }
          | DS number { pad($2); }
          | string { placeSection($1); }
 ;
@@ -195,6 +197,8 @@ try_again: // Can't use a `do {} while(0)` loop, otherwise compilers (wrongly) t
 		} else {
 			return yy::parser::make_YYEOF();
 		}
+	} else if (c == ',') {
+		return yy::parser::make_COMMA();
 	} else if (isNewline(c)) {
 		// Handle CRLF.
 		if (c == '\r' && context.file.sgetc() == '\n') {
@@ -374,12 +378,19 @@ static void alignTo(uint32_t alignment, uint32_t alignOfs) {
 	auto const &typeInfo = sectionTypeInfo[activeType];
 	auto &pc = curAddr[activeType][activeBankIdx];
 
-	// TODO: maybe warn if truncating?
-	alignOfs %= 1 << alignment;
+	if (alignment >= 16) {
+		scriptError(context, "Cannot align: The alignment (%" PRIu32
+				      ") must be less than 16\n", alignment);
+	}
+	uint32_t alignSize = 1u << alignment;
+	if (alignOfs >= alignSize) {
+		scriptError(context, "Cannot align: The alignment offset (%" PRIu32
+				      ") must be less than alignment size (%" PRIu32 ")\n",
+				      alignOfs, 1 << alignment);
+	}
 
 	assert(pc >= typeInfo.startAddr);
-	uint16_t length = alignment < 16 ? (uint16_t)(alignOfs - pc) % (1u << alignment)
-	                                 : alignOfs - pc; // Let it wrap around, this'll trip the check.
+	uint16_t length = (uint16_t)(alignOfs - pc) % alignSize;
 	if (uint16_t offset = pc - typeInfo.startAddr; length > typeInfo.size - offset) {
 		scriptError(context, "Cannot align: the next suitable address after $%04" PRIx16 " is $%04" PRIx16 ", past $%04" PRIx16,
 		            pc, (uint16_t)(pc + length), (uint16_t)(endaddr(activeType) + 1));

diff --git a/test/link/section-attributes-mismatch.out b/test/link/section-attributes-mismatch.out
@@ -1,2 +1,2 @@
-error: ./section-attributes-mismatch.link(3): The linker script assigns section "sec" to address $0018, but that would be ALIGN[4, 8] instead of the requested ALIGN[4, 0]
+error: ./section-attributes-mismatch.link(3): The linker script assigns section "sec" to address $0018, but that would be ALIGN[4, 8] instead of the requested ALIGN[4, 2]
 Linking failed with 1 error
diff --git a/test/link/section-attributes.asm b/test/link/section-attributes.asm
@@ -1,3 +1,3 @@
-SECTION "sec",ROM0,ALIGN[4]
-	ds 8, $42
+SECTION "sec",ROM0,ALIGN[4,2]
+	ds 6, $42
 SECTION "secfix",ROM0[$20]
diff --git a/test/link/section-attributes.link b/test/link/section-attributes.link
@@ -1,6 +1,7 @@
 ROM0
-	align 4
+	align 4, 2
 	"sec"
 	ds $18
 	org $20
+	align 5
 	"secfix"