From f9a5595dad438ee90b32ab11b1a72c3923c960c3 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 18 Dec 2016 10:19:24 -0500
Subject: [PATCH] Added seeking tests, correcting such errors as uncovered.

---
 .../PCMSegmentEventSourceTests.mm             | 33 +++++++++++++++++++
 Storage/Disk/PCMSegment.cpp                   |  8 +++--
 Storage/Storage.hpp                           | 19 +++++++++--
 3 files changed, 55 insertions(+), 5 deletions(-)

diff --git a/OSBindings/Mac/Clock SignalTests/PCMSegmentEventSourceTests.mm b/OSBindings/Mac/Clock SignalTests/PCMSegmentEventSourceTests.mm
index fde61678a..f40af2f28 100644
--- a/OSBindings/Mac/Clock SignalTests/PCMSegmentEventSourceTests.mm	
+++ b/OSBindings/Mac/Clock SignalTests/PCMSegmentEventSourceTests.mm	
@@ -77,4 +77,37 @@
 	[self assertFirstTwoEventLengthsForSource:segmentSource];
 }
 
+- (void)testSeekToSecondBit
+{
+	Storage::Disk::PCMSegmentEventSource segmentSource = self.segmentSource;
+	Storage::Time target_time(1, 10);
+
+	Storage::Time found_time = segmentSource.seek_to(target_time);
+	found_time.simplify();
+
+	XCTAssertTrue(found_time.length == 1 && found_time.clock_rate == 20, @"A request to seek to 1/10th should have seeked to 1/20th");
+
+	Storage::Disk::Track::Event next_event = segmentSource.get_next_event();
+	next_event.length.simplify();
+
+	XCTAssertTrue(next_event.length.length == 1 && next_event.length.clock_rate == 10, @"Next event should be 1/10th later");
+}
+
+- (void)testSeekBeyondFinalBit
+{
+	Storage::Disk::PCMSegmentEventSource segmentSource = self.segmentSource;
+	Storage::Time target_time(24, 10);
+
+	Storage::Time found_time = segmentSource.seek_to(target_time);
+	found_time.simplify();
+
+	XCTAssertTrue(found_time.length == 47 && found_time.clock_rate == 20, @"A request to seek to 24/10ths should have seeked to 47/20ths");
+
+	Storage::Disk::Track::Event next_event = segmentSource.get_next_event();
+	next_event.length.simplify();
+
+	XCTAssertTrue(next_event.length.length == 17 && next_event.length.clock_rate == 20, @"Next event should be 17/20ths later");
+	XCTAssertTrue(next_event.type == Storage::Disk::Track::Event::IndexHole, @"End should have been reached");
+}
+
 @end
diff --git a/Storage/Disk/PCMSegment.cpp b/Storage/Disk/PCMSegment.cpp
index 83f4dc203..fbf105363 100644
--- a/Storage/Disk/PCMSegment.cpp
+++ b/Storage/Disk/PCMSegment.cpp
@@ -77,10 +77,12 @@ Storage::Time PCMSegmentEventSource::seek_to(const Time &time_from_start)
 		return zero;
 	}
 
-	// adjust for time to get to bit zero and determine number of bits in
+	// adjust for time to get to bit zero and determine number of bits in;
+	// bit_pointer_ always records _the next bit_ that might trigger an event,
+	// so should be one beyond the one reached by a seek.
 	Time relative_time = time_from_start - half_bit_length;
-	bit_pointer_ = (relative_time / segment_.length_of_a_bit).get_unsigned_int();
+	bit_pointer_ = 1 + (relative_time / segment_.length_of_a_bit).get_unsigned_int();
 
 	// map up to the correct amount of time
-	return half_bit_length + segment_.length_of_a_bit * (unsigned int)bit_pointer_;
+	return half_bit_length + segment_.length_of_a_bit * (unsigned int)(bit_pointer_ - 1);
 }
diff --git a/Storage/Storage.hpp b/Storage/Storage.hpp
index 4e1ef640f..8077806fa 100644
--- a/Storage/Storage.hpp
+++ b/Storage/Storage.hpp
@@ -20,6 +20,7 @@ namespace Storage {
 struct Time {
 	unsigned int length, clock_rate;
 	Time() : length(0), clock_rate(1) {}
+	Time(unsigned int length, unsigned int clock_rate) : length(length), clock_rate(clock_rate) {}
 
 	/*!
 		Reduces this @c Time to its simplest form — eliminates all common factors from @c length
@@ -116,8 +117,8 @@ struct Time {
 	inline Time operator * (unsigned int multiplier) const
 	{
 		Time result;
-		result.clock_rate = clock_rate * multiplier;
-		result.length = length;
+		result.clock_rate = clock_rate;
+		result.length = length * multiplier;
 		return result;
 	}
 
@@ -142,6 +143,20 @@ struct Time {
 		return *this;
 	}
 
+	inline Time operator / (unsigned int divisor) const
+	{
+		Time result;
+		result.length = length;
+		result.clock_rate = clock_rate * divisor;
+		return result;
+	}
+
+	inline Time &operator /= (unsigned int divisor)
+	{
+		clock_rate *= divisor;
+		return *this;
+	}
+
 	inline void set_zero()
 	{
 		length = 0;