From f3e04aa7d49b275cdce51411bfe3a8b1c8d3f446 Mon Sep 17 00:00:00 2001
From: Kelvin Sherlock <ksherlock@gmail.com>
Date: Sat, 14 Dec 2019 16:16:48 -0500
Subject: [PATCH] add PFX command.

---
 link.cpp | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/link.cpp b/link.cpp
index c827fba..3eed87e 100644
--- a/link.cpp
+++ b/link.cpp
@@ -604,6 +604,16 @@ static std::string basename(const std::string &str) {
 	return str.substr(0, ix);
 }
 
+/* fixup GS/OS strings. */
+static void fix_path(std::string &s) {
+	for (char &c : s)
+		if (c == ':') c = '/';
+}
+
+/*
+ SEG name -> undocumented? command to set the OMF segment name (linker 3 only)
+
+ */
 void evaluate(label_t label, opcode_t opcode, const char *cursor) {
 
 	// todo - should move operand parsing to here.
@@ -674,6 +684,17 @@ void evaluate(label_t label, opcode_t opcode, const char *cursor) {
 			break;
 		}
 
+		case OP_PFX: {
+
+			std::string path = path_operand(cursor);
+			fix_path(path);
+
+			int ok = chdir(path.c_str());
+			if (ok < 0)
+				warn("PFX %s", path.c_str());
+			break;
+		}
+
 
 		case OP_TYP:
 			ftype = number_operand(cursor, file_types, OP_REQUIRED | OP_INSENSITIVE);