Implement unionized sections in RGBASM

This touched a lot more code than initially expected, for two reasons. First, this broke a big RGBASM assumption: that sections are always being written to at their end. This plus other problems required touching basically the entirety of `section.c`. Second, I tried different solutions to solve the above problem, and along the way I cleaned up many things around. (I believe that keeping this to "cleanup" commits yields subpar results, and since it's boring they get postponed anyways.) RGBLINK support still needs to be added, but this will come next.
2025-11-21 10:42:07 +00:00 · 2020-03-20 21:02:32 +01:00
parent 46a402f7d7
commit cb52ae0f26
13 changed files with 314 additions and 162 deletions
--- a/src/asm/section.c
+++ b/src/asm/section.c
@@ -16,16 +16,18 @@
 struct SectionStackEntry {
 	struct Section *pSection;
 	struct sSymbol *pScope; /* Section's symbol scope */
+	uint32_t offset;
 	struct SectionStackEntry *pNext;
 };

 struct SectionStackEntry *pSectionStack;
 static struct Section *currentLoadSection = NULL;
+uint32_t loadOffset = 0; /* The offset of the LOAD section within its parent */

 /*
 * A quick check to see if we have an initialized section
 */
-static void checksection(void)
+static inline void checksection(void)
 {
 	if (pCurrentSection == NULL)
 		fatalerror("Code generation before SECTION directive");
@@ -35,7 +37,7 @@ static void checksection(void)
 * A quick check to see if we have an initialized section that can contain
 * this much initialized data
 */
-static void checkcodesection(void)
+static inline void checkcodesection(void)
 {
 	checksection();

@@ -49,22 +51,20 @@ static void checkcodesection(void)
 /*
 * Check if the section has grown too much.
 */
-static void checksectionoverflow(uint32_t delta_size)
+static void reserveSpace(uint32_t delta_size)
 {
 	uint32_t maxSize = maxsize[pCurrentSection->nType];
-	uint32_t newSize = pCurrentSection->nPC + delta_size;
+	uint32_t newSize = curOffset + delta_size;

-	if (newSize > maxSize) {
-		/*
-		 * This check is here to trap broken code that generates
-		 * sections that are too big and to prevent the assembler from
-		 * generating huge object files or trying to allocate too much
-		 * memory.
-		 * The real check must be done at the linking stage.
-		 */
+	/*
+	 * This check is here to trap broken code that generates sections that
+	 * are too big and to prevent the assembler from generating huge object
+	 * files or trying to allocate too much memory.
+	 * A check at the linking stage is still necessary.
+	 */
+	if (newSize > maxSize)
 		fatalerror("Section '%s' is too big (max size = 0x%X bytes, reached 0x%X).",
 			   pCurrentSection->pzName, maxSize, newSize);
-	}
 }

 struct Section *out_FindSectionByName(const char *pzName)
@@ -85,7 +85,8 @@ struct Section *out_FindSectionByName(const char *pzName)
 * Find a section by name and type. If it doesn't exist, create it
 */
 static struct Section *getSection(char const *pzName, enum SectionType type,
-				  int32_t org, int32_t bank, int32_t alignment)
+				  uint32_t org, uint32_t bank,
+				  uint32_t alignment, bool isUnion)
 {
 	if (bank != -1) {
 		if (type != SECTTYPE_ROMX && type != SECTTYPE_VRAM
@@ -123,13 +124,99 @@ static struct Section *getSection(char const *pzName, enum SectionType type,
 	struct Section *pSect = out_FindSectionByName(pzName);

 	if (pSect) {
-		if (type == pSect->nType
-			&& ((uint32_t)org) == pSect->nOrg
-			&& ((uint32_t)bank) == pSect->nBank
-			&& ((uint32_t)alignment == pSect->nAlign)) {
-			return pSect;
+		unsigned int nbSectErrors = 0;
+#define fail(...) \
+	do { \
+		yyerror(__VA_ARGS__); \
+		nbSectErrors++; \
+	} while (0)
+
+		if (type != pSect->nType)
+			fail("Section \"%s\" already exists but with type %s",
+			     pSect->pzName, typeNames[pSect->nType]);
+
+		/*
+		 * Normal sections need to have exactly identical constraints;
+		 * but unionized sections only need "compatible" constraints,
+		 * and they end up with the strictest combination of both
+		 */
+		if (isUnion) {
+			if (!pSect->isUnion)
+				fail("Section \"%s\" already declared as non-union",
+				     pSect->pzName);
+			/*
+			 * WARNING: see comment abount assumption in
+			 * `EndLoadSection` if modifying the following check!
+			 */
+			if (sect_HasData(type))
+				fail("Cannot declare ROM sections as UNION");
+			if (org != -1) {
+				/* If neither is fixed, they must be the same */
+				if (pSect->nOrg != -1 && pSect->nOrg != org)
+					fail("Section \"%s\" already declared as fixed at different address $%x",
+					     pSect->pzName, pSect->nOrg);
+				else
+					/* Otherwise, just override */
+					pSect->nOrg = org;
+			} else if (alignment != 0) {
+				/* Make sure any fixed address is compatible */
+				if (pSect->nOrg != -1) {
+					uint32_t mask = alignment - 1;
+
+					if (pSect->nOrg & mask)
+						fail("Section \"%s\" already declared as fixed at incompatible address $%x",
+						     pSect->pzName,
+						     pSect->nOrg);
+				} else if (alignment > pSect->nAlign) {
+					/*
+					 * If the section is not fixed,
+					 * its alignment is the largest of both
+					 */
+					pSect->nAlign = alignment;
+				}
+			}
+			/* If the section's bank is unspecified, override it */
+			if (pSect->nBank == -1)
+				pSect->nBank = bank;
+			/* If both specify a bank, it must be the same one */
+			else if (bank != -1 && pSect->nBank != bank)
+				fail("Section \"%s\" already declared with different bank %u",
+				     pSect->pzName, pSect->nBank);
+		} else {
+			if (pSect->isUnion)
+				fail("Section \"%s\" already declared as union",
+				     pSect->pzName);
+			if (org != pSect->nOrg) {
+				if (pSect->nOrg == -1)
+					fail("Section \"%s\" already declared as floating",
+					     pSect->pzName);
+				else
+					fail("Section \"%s\" already declared as fixed at $%x",
+					     pSect->pzName, pSect->nOrg);
+			}
+			if (bank != pSect->nBank) {
+				if (pSect->nBank == -1)
+					fail("Section \"%s\" already declared as floating bank",
+					     pSect->pzName);
+				else
+					fail("Section \"%s\" already declared as fixed at bank %u",
+					     pSect->pzName, pSect->nBank);
+			}
+			if (alignment != pSect->nAlign) {
+				if (pSect->nAlign == 0)
+					fail("Section \"%s\" already declared as unaligned",
+					     pSect->pzName);
+				else
+					fail("Section \"%s\" already declared as aligned to %u bits",
+					     pSect->pzName, pSect->nAlign);
+			}
 		}
-		fatalerror("Section already exists but with a different type");
+
+		if (nbSectErrors)
+			fatalerror("Cannot create section \"%s\" (%u errors)",
+				   pSect->pzName, nbSectErrors);
+#undef fail
+		return pSect;
 	}

 	pSect = malloc(sizeof(*pSect));
@@ -141,7 +228,8 @@ static struct Section *getSection(char const *pzName, enum SectionType type,
 		fatalerror("Not enough memory for sectionname");

 	pSect->nType = type;
-	pSect->nPC = 0;
+	pSect->isUnion = isUnion;
+	pSect->size = 0;
 	pSect->nOrg = org;
 	pSect->nBank = bank;
 	pSect->nAlign = alignment;
@@ -177,10 +265,7 @@ static void setSection(struct Section *pSect)
 	if (nUnionDepth > 0)
 		fatalerror("Cannot change the section within a UNION");

-	nPC = (pSect != NULL) ? pSect->nPC : 0;
-
 	pPCSymbol->pSection = pSect;
-	pPCSymbol->isConstant = pSect && pSect->nOrg != -1;

 	sym_SetCurrentSymbolScope(NULL);
 }
@@ -188,24 +273,24 @@ static void setSection(struct Section *pSect)
 /*
 * Set the current section by name and type
 */
-void out_NewSection(char const *pzName, uint32_t type, int32_t org,
-		    struct SectionSpec const *attributes)
+void out_NewSection(char const *pzName, uint32_t type, uint32_t org,
+		    struct SectionSpec const *attributes, bool isUnion)
 {
 	if (currentLoadSection)
 		fatalerror("Cannot change the section within a `LOAD` block");

 	struct Section *pSect = getSection(pzName, type, org, attributes->bank,
-					   1 << attributes->alignment);
+					   1 << attributes->alignment, isUnion);

-	nPC = pSect->nPC;
 	setSection(pSect);
+	curOffset = isUnion ? 0 : pSect->size;
 	pCurrentSection = pSect;
 }

 /*
 * Set the current section by name and type
 */
-void out_SetLoadSection(char const *name, uint32_t type, int32_t org,
+void out_SetLoadSection(char const *name, uint32_t type, uint32_t org,
 			struct SectionSpec const *attributes)
 {
 	checkcodesection();
@@ -214,9 +299,10 @@ void out_SetLoadSection(char const *name, uint32_t type, int32_t org,
 		fatalerror("`LOAD` blocks cannot be nested");

 	struct Section *pSect = getSection(name, type, org, attributes->bank,
-					   1 << attributes->alignment);
+					   1 << attributes->alignment, false);

-	nPC = pSect->nPC;
+	loadOffset = curOffset;
+	curOffset = 0; /* curOffset -= loadOffset; */
 	setSection(pSect);
 	currentLoadSection = pSect;
 }
@@ -227,8 +313,9 @@ void out_EndLoadSection(void)
 		yyerror("Found `ENDL` outside of a `LOAD` block");
 	currentLoadSection = NULL;

-	nPC = pCurrentSection->nPC;
 	setSection(pCurrentSection);
+	curOffset += loadOffset;
+	loadOffset = 0;
 }

 struct Section *sect_GetSymbolSection(void)
@@ -236,15 +323,44 @@ struct Section *sect_GetSymbolSection(void)
 	return currentLoadSection ? currentLoadSection : pCurrentSection;
 }

-/*
- * Output an absolute byte (bypassing ROM/union checks)
- */
-static void absByteBypassCheck(uint8_t b)
+uint32_t sect_GetOutputOffset(void)
 {
-	pCurrentSection->tData[pCurrentSection->nPC++] = b;
-	if (currentLoadSection)
-		currentLoadSection->nPC++;
-	nPC++;
+	return curOffset + loadOffset;
+}
+
+static inline void growSection(uint32_t growth)
+{
+	curOffset += growth;
+	if (curOffset > pCurrentSection->size)
+		pCurrentSection->size = curOffset;
+	if (currentLoadSection && curOffset > currentLoadSection->size)
+		currentLoadSection->size = curOffset;
+}
+
+static inline void writebyte(uint8_t byte)
+{
+	pCurrentSection->tData[sect_GetOutputOffset()] = byte;
+	growSection(1);
+}
+
+static inline void writeword(uint16_t b)
+{
+	writebyte(b & 0xFF);
+	writebyte(b >> 8);
+}
+
+static inline void writelong(uint32_t b)
+{
+	writebyte(b & 0xFF);
+	writebyte(b >> 8);
+	writebyte(b >> 16);
+	writebyte(b >> 24);
+}
+
+static inline void createPatch(enum PatchType type,
+			       struct Expression const *expr)
+{
+	out_CreatePatch(type, expr, sect_GetOutputOffset());
 }

 /*
@@ -253,16 +369,18 @@ static void absByteBypassCheck(uint8_t b)
 void out_AbsByte(uint8_t b)
 {
 	checkcodesection();
-	checksectionoverflow(1);
-	absByteBypassCheck(b);
+	reserveSpace(1);
+
+	writebyte(b);
 }

 void out_AbsByteGroup(uint8_t const *s, int32_t length)
 {
 	checkcodesection();
-	checksectionoverflow(length);
+	reserveSpace(length);
+
 	while (length--)
-		absByteBypassCheck(*s++);
+		writebyte(*s++);
 }

 /*
@@ -271,19 +389,17 @@ void out_AbsByteGroup(uint8_t const *s, int32_t length)
 void out_Skip(int32_t skip)
 {
 	checksection();
-	checksectionoverflow(skip);
+	reserveSpace(skip);
+
 	if (!sect_HasData(pCurrentSection->nType)) {
-		pCurrentSection->nPC += skip;
-		if (currentLoadSection)
-			currentLoadSection->nPC += skip;
-		nPC += skip;
+		growSection(skip);
 	} else if (nUnionDepth > 0) {
 		while (skip--)
-			absByteBypassCheck(CurrentOptions.fillchar);
+			writebyte(CurrentOptions.fillchar);
 	} else {
 		checkcodesection();
 		while (skip--)
-			absByteBypassCheck(CurrentOptions.fillchar);
+			writebyte(CurrentOptions.fillchar);
 	}
 }

@@ -293,19 +409,10 @@ void out_Skip(int32_t skip)
 void out_String(char const *s)
 {
 	checkcodesection();
-	checksectionoverflow(strlen(s));
-	while (*s)
-		absByteBypassCheck(*s++);
-}
+	reserveSpace(strlen(s));

-static void outputExpression(struct Expression const *expr)
-{
-	if (!rpn_isKnown(expr)) {
-		out_CreatePatch(PATCHTYPE_BYTE, expr);
-		out_AbsByte(0);
-	} else {
-		out_AbsByte(expr->nVal);
-	}
+	while (*s)
+		writebyte(*s++);
 }

 /*
@@ -314,7 +421,15 @@ static void outputExpression(struct Expression const *expr)
 */
 void out_RelByte(struct Expression *expr)
 {
-	outputExpression(expr);
+	checkcodesection();
+	reserveSpace(1);
+
+	if (!rpn_isKnown(expr)) {
+		createPatch(PATCHTYPE_BYTE, expr);
+		writebyte(0);
+	} else {
+		writebyte(expr->nVal);
+	}
 	rpn_Free(expr);
 }

@@ -322,25 +437,20 @@ void out_RelByte(struct Expression *expr)
 * Output several copies of a relocatable byte. Checking will be done to see if
 * it is an absolute value in disguise.
 */
-void out_RelBytes(struct Expression *expr, int32_t n)
-{
-	while (n--)
-		outputExpression(expr);
-	rpn_Free(expr);
-}
-
-/*
- * Output an absolute word
- */
-static void absWord(uint16_t b)
+void out_RelBytes(struct Expression *expr, uint32_t n)
 {
 	checkcodesection();
-	checksectionoverflow(2);
-	pCurrentSection->tData[pCurrentSection->nPC++] = b & 0xFF;
-	pCurrentSection->tData[pCurrentSection->nPC++] = b >> 8;
-	if (currentLoadSection)
-		currentLoadSection->nPC += 2;
-	nPC += 2;
+	reserveSpace(n);
+
+	while (n--) {
+		if (!rpn_isKnown(expr)) {
+			createPatch(PATCHTYPE_BYTE, expr);
+			writebyte(0);
+		} else {
+			writebyte(expr->nVal);
+		}
+	}
+	rpn_Free(expr);
 }

 /*
@@ -349,42 +459,32 @@ static void absWord(uint16_t b)
 */
 void out_RelWord(struct Expression *expr)
 {
+	checkcodesection();
+	reserveSpace(2);
+
 	if (!rpn_isKnown(expr)) {
-		out_CreatePatch(PATCHTYPE_WORD, expr);
-		absWord(0);
+		createPatch(PATCHTYPE_WORD, expr);
+		writeword(0);
 	} else {
-		absWord(expr->nVal);
+		writeword(expr->nVal);
 	}
 	rpn_Free(expr);
 }

-/*
- * Output an absolute longword
- */
-static void absLong(uint32_t b)
-{
-	checkcodesection();
-	checksectionoverflow(4);
-	pCurrentSection->tData[pCurrentSection->nPC++] = b & 0xFF;
-	pCurrentSection->tData[pCurrentSection->nPC++] = b >> 8;
-	pCurrentSection->tData[pCurrentSection->nPC++] = b >> 16;
-	pCurrentSection->tData[pCurrentSection->nPC++] = b >> 24;
-	if (currentLoadSection)
-		currentLoadSection->nPC += 4;
-	nPC += 4;
-}
-
 /*
 * Output a relocatable longword. Checking will be done to see if
 * is an absolute value in disguise.
 */
 void out_RelLong(struct Expression *expr)
 {
+	checkcodesection();
+	reserveSpace(2);
+
 	if (!rpn_isKnown(expr)) {
-		out_CreatePatch(PATCHTYPE_LONG, expr);
-		absLong(0);
+		createPatch(PATCHTYPE_LONG, expr);
+		writelong(0);
 	} else {
-		absLong(expr->nVal);
+		writelong(expr->nVal);
 	}
 	rpn_Free(expr);
 }
@@ -396,13 +496,11 @@ void out_RelLong(struct Expression *expr)
 void out_PCRelByte(struct Expression *expr)
 {
 	checkcodesection();
-	checksectionoverflow(1);
+	reserveSpace(1);
+
 	if (!rpn_isKnown(expr) || pCurrentSection->nOrg == -1) {
-		out_CreatePatch(PATCHTYPE_JR, expr);
-		pCurrentSection->tData[pCurrentSection->nPC++] = 0;
-		if (currentLoadSection)
-			currentLoadSection->nPC++;
-		nPC++;
+		createPatch(PATCHTYPE_JR, expr);
+		writebyte(0);
 	} else {
 		/* Target is relative to the byte *after* the operand */
 		uint16_t address = sym_GetValue(pPCSymbol) + 1;
@@ -412,9 +510,9 @@ void out_PCRelByte(struct Expression *expr)
 		if (offset < -128 || offset > 127) {
 			yyerror("jr target out of reach (expected -129 < %d < 128)",
 				offset);
-			out_AbsByte(0);
+			writebyte(0);
 		} else {
-			out_AbsByte(offset);
+			writebyte(offset);
 		}
 	}
 	rpn_Free(expr);
@@ -444,7 +542,7 @@ void out_BinaryFile(char const *s)
 		fsize = ftell(f);
 		rewind(f);

-		checksectionoverflow(fsize);
+		reserveSpace(fsize);
 	} else if (errno != ESPIPE) {
 		yyerror("Error determining size of INCBIN file '%s': %s", s,
 			strerror(errno));
@@ -452,11 +550,8 @@ void out_BinaryFile(char const *s)

 	while ((byte = fgetc(f)) != EOF) {
 		if (fsize == -1)
-			checksectionoverflow(1);
-		pCurrentSection->tData[pCurrentSection->nPC++] = byte;
-		if (currentLoadSection)
-			currentLoadSection->nPC++;
-		nPC++;
+			growSection(1);
+		writebyte(byte);
 	}

 	if (ferror(f))
@@ -493,7 +588,7 @@ void out_BinaryFileSlice(char const *s, int32_t start_pos, int32_t length)
 	}

 	checkcodesection();
-	checksectionoverflow(length);
+	reserveSpace(length);

 	int32_t fsize;

@@ -524,10 +619,7 @@ void out_BinaryFileSlice(char const *s, int32_t start_pos, int32_t length)
 		int byte = fgetc(f);

 		if (byte != EOF) {
-			pCurrentSection->tData[pCurrentSection->nPC++] = byte;
-			if (currentLoadSection)
-				currentLoadSection->nPC++;
-			nPC++;
+			writebyte(byte);
 		} else if (ferror(f)) {
 			yyerror("Error reading INCBIN file '%s': %s", s,
 				strerror(errno));
@@ -553,6 +645,7 @@ void out_PushSection(void)

 	pSect->pSection = pCurrentSection;
 	pSect->pScope = sym_GetCurrentSymbolScope();
+	pSect->offset = curOffset;
 	pSect->pNext = pSectionStack;
 	pSectionStack = pSect;
 }
@@ -571,6 +664,8 @@ void out_PopSection(void)
 	setSection(pSect->pSection);
 	pCurrentSection = pSect->pSection;
 	sym_SetCurrentSymbolScope(pSect->pScope);
+	curOffset = pSect->offset;
+
 	pSectionStack = pSect->pNext;
 	free(pSect);
 }