add: start nasm code gen

1 files changed, 91 insertions, 0 deletions

diff --git a/src/codegen/nasm.c b/src/codegen/nasm.c
index 0782ee1..37d13a7 100644
--- a/src/codegen/nasm.c
+++ b/src/codegen/nasm.c
@@ -1,5 +1,7 @@
 #include <stdio.h>
 #include <stddef.h>
+#include <string.h>
+#include <stdbool.h>
 
 #include "codegen/nasm.h"
 
@@ -32,6 +34,89 @@ static void emit_data(struct Program* program, FILE* out)
 	}
 }
 
+static const char* assign_mnemonic(enum TokenType op)
+{
+	switch (op)
+	{
+		case TOKEN_EQUAL:      return "mov";
+		case TOKEN_PLUS_EQUAL:  return "add";
+		case TOKEN_MINUS_EQUAL: return "sub";
+		case TOKEN_STAR_EQUAL:  return "imul";
+		default:               return NULL;
+	}
+}
+
+static bool emit_operand(struct Expr* expr, FILE* out)
+{
+	switch (expr->kind)
+	{
+		case EXPR_PRIMARY:
+			fprintf(out, "%.*s", (int)expr->primary.token.length, expr->primary.token.start);
+			return true;
+		case EXPR_MEMBER:
+			if (!emit_operand(expr->member.object, out))
+				return false;
+			fprintf(out, ".%.*s", (int)expr->member.member.length, expr->member.member.start);
+			return true;
+		case EXPR_BINARY:
+			return false;
+	}
+
+	return false;
+}
+
+static void emit_assign(struct AssignStatement* assign, FILE* out)
+{
+	const char* mnemonic = assign_mnemonic(assign->op.type);
+	if (mnemonic == NULL || assign->value->kind == EXPR_BINARY)
+	{
+		fprintf(out, "\t; TODO: unsupported assignment\n");
+		return;
+	}
+
+	if (assign->target_deref)
+		fprintf(out, "\t%s [%.*s], ", mnemonic, (int)assign->target.length, assign->target.start);
+	else
+		fprintf(out, "\t%s %.*s, ", mnemonic, (int)assign->target.length, assign->target.start);
+
+	emit_operand(assign->value, out);
+	fprintf(out, "\n");
+}
+
+static void emit_statement(struct Statement* statement, FILE* out)
+{
+	switch (statement->kind)
+	{
+		case STATEMENT_ASSIGN:
+			emit_assign(&statement->assign, out);
+			break;
+		case STATEMENT_LABEL:
+			fprintf(out, "%.*s:\n", (int)statement->label.name.length, statement->label.name.start);
+			break;
+		case STATEMENT_GOTO:
+			fprintf(out, "\tjmp %.*s\n", (int)statement->jump.label.length, statement->jump.label.start);
+			break;
+		case STATEMENT_SYSCALL:
+			fprintf(out, "\tsyscall\n");
+			break;
+		default:
+			fprintf(out, "\t; TODO: unsupported statement\n");
+			break;
+	}
+}
+
+static void emit_proc(struct ProcDecl* proc, FILE* out)
+{
+	bool is_entry = proc->name.length == 4 && memcmp(proc->name.start, "main", 4) == 0;
+	if (is_entry)
+		fprintf(out, "_start:\n");
+	else
+		fprintf(out, "%.*s:\n", (int)proc->name.length, proc->name.start);
+
+	for (size_t i = 0; i < proc->body_count; i += 1)
+		emit_statement(&proc->body[i], out);
+}
+
 void generate_nasm(struct Program* program, FILE* out)
 {
 	if (program->const_count > 0)
@@ -45,4 +130,10 @@ void generate_nasm(struct Program* program, FILE* out)
 
 	fprintf(out, "section .text\n");
 	fprintf(out, "global _start\n");
+
+	for (size_t i = 0; i < program->proc_count; i += 1)
+	{
+		fprintf(out, "\n");
+		emit_proc(&program->procs[i], out);
+	}
 }