From 390f49ba23a8dea54e05b5610d4bae0a0611da0e Mon Sep 17 00:00:00 2001
From: Rangi42 <remy.oukaour+rangi42@gmail.com>
Date: Wed, 25 Oct 2023 20:39:48 -0400
Subject: [PATCH] [in progress] Implement `ds align[]`

---
 include/asm/lexer.h |  6 ++++++
 src/asm/parser.y    | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/include/asm/lexer.h b/include/asm/lexer.h
index 91bb0a8ec6..239b3e4f0a 100644
--- 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
index 89d6164a1c..737f8ff35d 100644
--- 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 {