From ca53fac73256c26ecccab7ef8492df32be45c6ff Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 26 Sep 2016 21:20:30 -0400
Subject: [PATCH] Switched to assuming a single-sided disk, moved out magic
 constants.

---
 Storage/Disk/Formats/AcornADF.cpp | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/Storage/Disk/Formats/AcornADF.cpp b/Storage/Disk/Formats/AcornADF.cpp
index 13956ed3d..c82d27e65 100644
--- a/Storage/Disk/Formats/AcornADF.cpp
+++ b/Storage/Disk/Formats/AcornADF.cpp
@@ -11,6 +11,11 @@
 #include <sys/stat.h>
 #include "../Encodings/MFM.hpp"
 
+namespace {
+	static const unsigned int sectors_per_track = 16;
+	static const unsigned int bytes_per_sector = 256;
+}
+
 using namespace Storage::Disk;
 
 AcornADF::AcornADF(const char *file_name) : _file(nullptr)
@@ -20,8 +25,8 @@ AcornADF::AcornADF(const char *file_name) : _file(nullptr)
 
 	// very loose validation: the file needs to be a multiple of 256 bytes
 	// and not ungainly large
-	if(file_stats.st_size & 255) throw ErrorNotAcornADF;
-	if(file_stats.st_size < 7 * 256) throw ErrorNotAcornADF;
+	if(file_stats.st_size % bytes_per_sector) throw ErrorNotAcornADF;
+	if(file_stats.st_size < 7 * bytes_per_sector) throw ErrorNotAcornADF;
 
 	_file = fopen(file_name, "rb");
 	if(!_file) throw ErrorCantOpen;
@@ -49,7 +54,7 @@ unsigned int AcornADF::get_head_position_count()
 
 unsigned int AcornADF::get_head_count()
 {
-	return 2;
+	return 1;
 }
 
 std::shared_ptr<Track> AcornADF::get_track_at_position(unsigned int head, unsigned int position)
@@ -57,19 +62,19 @@ std::shared_ptr<Track> AcornADF::get_track_at_position(unsigned int head, unsign
 	std::shared_ptr<Track> track;
 
 	if(head >= 2) return track;
-	long file_offset = (position * 2 + head) * 256 * 16;
+	long file_offset = (position * 1 + head) * bytes_per_sector * sectors_per_track;
 	fseek(_file, file_offset, SEEK_SET);
 
 	std::vector<Storage::Encodings::MFM::Sector> sectors;
-	for(int sector = 0; sector < 16; sector++)
+	for(int sector = 0; sector < sectors_per_track; sector++)
 	{
 		Storage::Encodings::MFM::Sector new_sector;
 		new_sector.track = (uint8_t)position;
-		new_sector.side = 0;
+		new_sector.side = (uint8_t)head;
 		new_sector.sector = (uint8_t)sector;
 
-		new_sector.data.resize(256);
-		fread(&new_sector.data[0], 1, 256, _file);
+		new_sector.data.resize(bytes_per_sector);
+		fread(&new_sector.data[0], 1, bytes_per_sector, _file);
 		if(feof(_file))
 			break;