Implement [[ inline code blocks ]]

Fixes #500

include/asm/section.h

@@ -56,6 +56,9 @@ void sect_NextUnionMember(void);
 void sect_EndUnion(void);
 void sect_CheckUnionClosed(void);
 
+char *sect_StartInlineBlock(void);
+void sect_EndInlineBlock(void);
+
 void out_AbsByte(uint8_t b);
 void out_AbsByteGroup(uint8_t const *s, int32_t length);
 void out_AbsWordGroup(uint8_t const *s, int32_t length);

src/asm/lexer.c

@@ -1650,10 +1650,6 @@ static int yylex_NORMAL(void)
 			yylval.tzSym[1] = '\0';
 			return T_ID;
 
-		case '[':
-			return T_LBRACK;
-		case ']':
-			return T_RBRACK;
 		case '(':
 			return T_LPAREN;
 		case ')':
@@ -1663,6 +1659,18 @@ static int yylex_NORMAL(void)
 
 		/* Handle ambiguous 1- or 2-char tokens */
 
+		case '[': /* Either [ or [[ */
+			if (peek(0) == '[') {
+				shiftChars(1);
+				return T_2LBRACK;
+			}
+			return T_LBRACK;
+		case ']': /* Either ] or ]] */
+			if (peek(0) == ']') {
+				shiftChars(1);
+				return T_2RBRACK;
+			}
+			return T_RBRACK;
 		case '*': /* Either MUL or EXP */
 			if (peek(0) == '*') {
 				shiftChars(1);

src/asm/parser.y

@@ -406,6 +406,11 @@ enum {
 		int32_t step;
 	} forArgs;
 	struct StrFmtArgList strfmtArgs;
+	struct {
+		char *name;
+		int32_t nPCOffset;
+		uint32_t nListCountEmpty;
+	} inlineBlock;
 }
 
 %type	<sVal>		relocexpr
@@ -429,12 +434,15 @@ enum {
 %type	<nConstValue>	sectorg
 %type	<sectSpec>	sectattrs
 
+%type	<inlineBlock>	inline_block
+
 %token	<nConstValue>	T_NUMBER "number"
 %token	<tzString>	T_STRING "string"
 
 %token	T_COMMA ","
 %token	T_COLON ":"
 %token	T_LBRACK "[" T_RBRACK "]"
+%token	T_2LBRACK "[[" T_2RBRACK "]]"
 %token	T_LPAREN "(" T_RPAREN ")"
 %token	T_NEWLINE "newline"
 
@@ -1185,6 +1193,10 @@ reloc_16bit	: relocexpr {
 				warning(WARNING_TRUNCATION, "Expression must be 16-bit\n");
 			$$ = $1;
 		}
+		| inline_block {
+			rpn_Symbol(&$$, $1.name);
+			free($1.name);
+		}
 ;
 
 reloc_16bit_no_str : relocexpr_no_str {
@@ -1193,8 +1205,23 @@ reloc_16bit_no_str : relocexpr_no_str {
 				warning(WARNING_TRUNCATION, "Expression must be 16-bit\n");
 			$$ = $1;
 		}
+		| inline_block {
+			rpn_Symbol(&$$, $1.name);
+			free($1.name);
+		}
 ;
 
+inline_block	: T_2LBRACK T_NEWLINE {
+			$<inlineBlock>$.name = sect_StartInlineBlock();
+			$<inlineBlock>$.nPCOffset = nPCOffset;
+			$<inlineBlock>$.nListCountEmpty = nListCountEmpty;
+		} lines T_2RBRACK {
+			sect_EndInlineBlock();
+			$$.name = $<inlineBlock>3.name;
+			nPCOffset = $<inlineBlock>3.nPCOffset;
+			nListCountEmpty = $<inlineBlock>3.nListCountEmpty;
+		}
+;
 
 relocexpr	: relocexpr_no_str
 		| string {

src/asm/section.c

@@ -31,6 +31,8 @@ uint32_t curOffset; /* Offset into the current section (see sect_GetSymbolOffset
 static struct Section *currentLoadSection = NULL;
 uint32_t loadOffset; /* The offset of the LOAD section within its parent */
 
+static uint32_t inlineBlockID = 0; /* Incrementing unique ID for inline block labels */
+
 struct UnionStackEntry {
 	uint32_t start;
 	uint32_t size;
@@ -492,6 +494,62 @@ void sect_CheckUnionClosed(void)
 		error("Unterminated UNION construct!\n");
 }
 
+char *sect_StartInlineBlock(void)
+{
+	checkcodesection();
+
+	if (currentLoadSection)
+		fatalerror("`LOAD` blocks cannot contain inline blocks\n");
+
+	struct Section *sect = pCurrentSection;
+
+	/*
+	 * Inline blocks are section fragments, so the section containing them
+	 * has to become a fragment too.
+	 */
+	sect->modifier = SECTION_FRAGMENT;
+
+	struct SectionSpec attrs;
+
+	// 'SECTION "...", ROM0, BANK[0]' is not allowed
+	attrs.bank = sect->bank == 0 ? -1 : sect->bank;
+	attrs.alignment = 0;
+	attrs.alignOfs = 0;
+
+	/*
+	 * Initialize the inline block's section with a unique name so out_NewSection
+	 * won't just find the current existing section.
+	 */
+	char *name = malloc(24); // space for "inline_block$4294967295" + '\0'
+
+	if (name == NULL)
+		fatalerror("Not enough memory for inline block name: %s\n", strerror(errno));
+
+	sprintf(name, "inline_block$%" PRIu32, inlineBlockID++);
+
+	out_PushSection();
+	out_NewSection(name, sect->type, -1, &attrs, SECTION_FRAGMENT);
+
+	/*
+	 * Rename the inline block's section fragment to match the current section
+	 * so they'll be merged.
+	 */
+	free(pCurrentSection->name);
+	pCurrentSection->name = strdup(sect->name);
+	if (pCurrentSection->name == NULL)
+		fatalerror("Not enough memory for inline block name: %s\n", strerror(errno));
+
+	// Label the start of the inline block to get its address.
+	sym_AddLabel(name);
+
+	return name;
+}
+
+void sect_EndInlineBlock(void)
+{
+	out_PopSection();
+}
+
 /*
  * Output an absolute byte
  */