Allow STARTOF(SECTTYPE) and SIZEOF(SECTTYPE) to be constant when possible (#2131)

man/rgbasm.5

@@ -772,7 +772,15 @@ and no longer the current section).
 If
 .Ar arg
 is a section type keyword, it returns the size of that section type.
-The result is not constant, since only RGBLINK can compute its value.
+The result is a known constant except for
+.Ic ROM0
+and
+.Ic WRAM0 ,
+since their sizes may be affected by RGBLINK options
+.Fl t
+and
+.Fl w
+respectively.
 .Pp
 If
 .Ar arg
@@ -786,7 +794,8 @@ The result is a known constant if the section has a fixed address.
 If
 .Ar arg
 is a section type keyword, it returns the starting address of that section type.
-The result is not constant, since only RGBLINK can compute its value.
+.Pp
+The result is always a known constant at assembly time.
 .El
 .Sh SECTIONS
 Before you can start writing code, you must define a section.

src/asm/rpn.cpp

@@ -142,14 +142,20 @@ void Expression::makeStartOfSection(std::string const &sectName) {
 
 void Expression::makeSizeOfSectionType(SectionType type) {
 	assume(rpn.empty());
-	data = "Section type's size is not known";
-	rpn.emplace_back(RPN_SIZEOF_SECTTYPE, static_cast<uint8_t>(type));
+	if (type == SECTTYPE_WRAM0) {
+		data = "Section type WRAM0's size is not known (can be affected by RGBLINK '-w/--wramx')";
+		rpn.emplace_back(RPN_SIZEOF_SECTTYPE, static_cast<uint8_t>(type));
+	} else if (type == SECTTYPE_ROM0) {
+		data = "Section type ROM0's size is not known (can be affected by RGBLINK '-t/--tiny')";
+		rpn.emplace_back(RPN_SIZEOF_SECTTYPE, static_cast<uint8_t>(type));
+	} else {
+		data = static_cast<int32_t>(sectionTypeInfo[type].size);
+	}
 }
 
 void Expression::makeStartOfSectionType(SectionType type) {
 	assume(rpn.empty());
-	data = "Section type's start is not known";
-	rpn.emplace_back(RPN_STARTOF_SECTTYPE, static_cast<uint8_t>(type));
+	data = static_cast<int32_t>(sectionTypeInfo[type].startAddr);
 }
 
 static bool tryConstZero(Expression const &lhs, Expression const &rhs) {

test/asm/secttype-sizeof-startof-unknown.asm

@@ -0,0 +1,5 @@
+SECTION "ROM0", ROM0[STARTOF(ROM0)]
+Label:: ds SIZEOF(ROM0)
+
+SECTION "WRAM0", WRAM0[STARTOF(WRAM0)]
+wLabel:: ds SIZEOF(WRAM0)

test/asm/secttype-sizeof-startof-unknown.err

@@ -0,0 +1,5 @@
+error: Expected constant expression: Section type ROM0's size is not known (can be affected by RGBLINK '-t/--tiny')
+    at secttype-sizeof-startof-unknown.asm(2)
+error: Expected constant expression: Section type WRAM0's size is not known (can be affected by RGBLINK '-w/--wramx')
+    at secttype-sizeof-startof-unknown.asm(5)
+Assembly aborted with 2 errors

test/asm/secttype-sizeof-startof.asm

@@ -0,0 +1,13 @@
+SECTION "ROMX", ROMX[STARTOF(ROMX)], BANK[1]
+xLabel:: ds SIZEOF(ROMX), $22
+
+SECTION "VRAM", VRAM[STARTOF(VRAM)], BANK[0]
+vLabel:: ds SIZEOF(VRAM)
+
+SECTION "ROM0", ROM0[STARTOF(ROM0)]
+ASSERT !ISCONST(SIZEOF(ROM0))  ; rgblink may have -t/--tiny
+Label:: ds $4000, $11
+
+SECTION "WRAM0", WRAM0[STARTOF(WRAM0)]
+ASSERT !ISCONST(SIZEOF(WRAM0)) ; rgblink may have -w/--wramx
+wLabel:: ds $1000

test/asm/secttype-sizeof-startof.out.bin

@@ -0,0 +1 @@
+Line truncated