add: start code gen

1 files changed, 48 insertions, 0 deletions

diff --git a/src/codegen/nasm.c b/src/codegen/nasm.c
new file mode 100644
index 0000000..0782ee1
--- /dev/null
+++ b/src/codegen/nasm.c
@@ -0,0 +1,48 @@
+#include <stdio.h>
+#include <stddef.h>
+
+#include "codegen/nasm.h"
+
+static void emit_consts(struct Program* program, FILE* out)
+{
+	for (size_t i = 0; i < program->const_count; i += 1)
+	{
+		struct ConstDecl decl = program->consts[i];
+		fprintf(out, "%.*s equ %.*s\n",
+			(int)decl.name.length, decl.name.start,
+			(int)decl.value.length, decl.value.start);
+	}
+}
+
+static void emit_data(struct Program* program, FILE* out)
+{
+	fprintf(out, "section .data\n");
+
+	for (size_t i = 0; i < program->data_count; i += 1)
+	{
+		struct DataDecl decl = program->data_decls[i];
+
+		// the value lexeme keeps its surrounding double quotes; NASM backtick
+		// strings interpret the same escapes, so re-wrap the inner content
+		fprintf(out, "%.*s: db `%.*s`\n",
+			(int)decl.name.length, decl.name.start,
+			(int)(decl.value.length - 2), decl.value.start + 1);
+		fprintf(out, ".len equ $ - %.*s\n",
+			(int)decl.name.length, decl.name.start);
+	}
+}
+
+void generate_nasm(struct Program* program, FILE* out)
+{
+	if (program->const_count > 0)
+	{
+		emit_consts(program, out);
+		fprintf(out, "\n");
+	}
+
+	emit_data(program, out);
+	fprintf(out, "\n");
+
+	fprintf(out, "section .text\n");
+	fprintf(out, "global _start\n");
+}