[in progress] Implement ds align[]

gbdev · Oct 26, 2023 · 390f49b · 390f49b
1 parent 944c5f0
commit 390f49b
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Showing 2 changed files with 42 additions and 0 deletions.
diff --git a/include/asm/lexer.h b/include/asm/lexer.h
@@ -90,6 +90,12 @@ int yylex(void);
 bool lexer_CaptureRept(struct CaptureBody *capture);
 bool lexer_CaptureMacroBody(struct CaptureBody *capture);
 
+struct DsAlignment {
+	uint32_t nbBytes;
+	uint8_t alignment;
+	uint16_t alignOfs;
+};
+
 #define INITIAL_DS_ARG_SIZE 2
 struct DsArgList {
 	size_t nbArgs;

diff --git a/src/asm/parser.y b/src/asm/parser.y
@@ -509,6 +509,7 @@ enum {
 	struct SectionSpec sectSpec;
 	struct MacroArgs *macroArg;
 	enum AssertionType assertType;
+	struct DsAlignment dsAlign;
 	struct DsArgList dsArgs;
 	struct PurgeArgList purgeArgs;
 	struct {
@@ -664,6 +665,7 @@ enum {
 %type	<sectMod> sectmod
 %type	<macroArg> macroargs
 
+%type	<dsAlign> ds_align
 %type	<dsArgs> ds_args
 
 %type	<purgeArgs> purge_args
@@ -1169,6 +1171,40 @@ ds		: T_POP_DS uconst { sect_Skip($2, true); }
 			sect_RelBytes($2, $4.args, $4.nbArgs);
 			freeDsArgList(&$4);
 		}
+		| T_POP_DS ds_align trailing_comma {
+			sect_Skip($2.nbBytes, true);
+			sect_AlignPC($2.alignment, $2.alignOfs);
+		}
+		| T_POP_DS ds_align T_COMMA ds_args trailing_comma {
+			sect_RelBytes($2.nbBytes, $4.args, $4.nbArgs);
+			sect_AlignPC($2.alignment, $2.alignOfs);
+			freeDsArgList(&$4);
+		}
+;
+
+ds_align	: T_OP_ALIGN T_LBRACK uconst T_RBRACK {
+			if ($3 > 16) {
+				error("Alignment must be between 0 and 16, not %u\n", $3);
+			} else {
+				uint32_t mask = (1 << $3) - 1;
+
+				// TODO: correct formula; sym_GetPCValue() won't work in floating sections
+				$$.alignment = $3;
+				$$.nbBytes = (mask + 1 - (sym_GetPCValue() & mask)) & mask;
+			}
+		}
+		| T_OP_ALIGN T_LBRACK uconst T_COMMA uconst T_RBRACK {
+			if ($3 > 16) {
+				error("Alignment must be between 0 and 16, not %u\n", $3);
+			} else if ($5 >= 1 << $3) {
+				error("Offset must be between 0 and %u, not %u\n",
+					(1 << $3) - 1, $5);
+			} else {
+				$$.alignment = $3;
+				$$.alignOfs = $5;
+				$$.nbBytes = 0; // TODO: correct formula
+			}
+		}
 ;
 
 ds_args		: reloc_8bit {