From c8c1792c3f83889e3f8da570e6c949a5430b5d2c Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Thu, 17 Aug 2017 22:20:02 -0400
Subject: [PATCH] Made a first attempt at HFE support.

---
 Storage/Disk/Formats/HFE.cpp | 36 ++++++++++++++++++++++++++++++++++--
 Storage/Disk/Formats/HFE.hpp |  1 +
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/Storage/Disk/Formats/HFE.cpp b/Storage/Disk/Formats/HFE.cpp
index 00c837669..38c624fb8 100644
--- a/Storage/Disk/Formats/HFE.cpp
+++ b/Storage/Disk/Formats/HFE.cpp
@@ -8,11 +8,20 @@
 
 #include "HFE.hpp"
 
+#include "../PCMTrack.hpp"
+
 using namespace Storage::Disk;
 
 HFE::HFE(const char *file_name) :
 		Storage::FileHolder(file_name) {
-	throw ErrorNotHFE;
+	if(!check_signature("HXCPICFE", 8)) throw ErrorNotHFE;
+
+	if(fgetc(file_)) throw ErrorNotHFE;
+	track_count_ = (unsigned int)fgetc(file_);
+	head_count_ = (unsigned int)fgetc(file_);
+
+	fseek(file_, 7, SEEK_CUR);
+	track_list_offset_ = (long)fgetc16le() << 9;
 }
 
 HFE::~HFE() {
@@ -31,5 +40,28 @@ bool HFE::get_is_read_only() {
 }
 
 std::shared_ptr<Track> HFE::get_uncached_track_at_position(unsigned int head, unsigned int position) {
-	return nullptr;
+	// Get track position and length from the lookup table; data is then always interleaved
+	// based on an assumption of two heads.
+	fseek(file_, track_list_offset_ + position * 4, SEEK_SET);
+
+	long track_offset = (long)fgetc16le() << 9;
+	uint16_t track_length = fgetc16le();
+
+	fseek(file_, track_offset, SEEK_SET);
+	if(head) fseek(file_, 256, SEEK_CUR);
+
+	PCMSegment segment;
+	uint16_t side_length = track_length / 2;
+	segment.data.resize(side_length);
+
+	uint16_t c = 0;
+	while(c < side_length) {
+		uint16_t length = (uint16_t)std::min(256, side_length - c);
+		fread(&segment.data[c], 1, length, file_);
+		c += length;
+		fseek(file_, 256, SEEK_CUR);
+	}
+
+	std::shared_ptr<Track> track(new PCMTrack(segment));
+	return track;
 }
diff --git a/Storage/Disk/Formats/HFE.hpp b/Storage/Disk/Formats/HFE.hpp
index 6dc2d4888..504140d9b 100644
--- a/Storage/Disk/Formats/HFE.hpp
+++ b/Storage/Disk/Formats/HFE.hpp
@@ -43,6 +43,7 @@ class HFE: public Disk, public Storage::FileHolder {
 
 		unsigned int head_count_;
 		unsigned int track_count_;
+		long track_list_offset_;
 };
 
 }