From e15d6717a1e92a2317aa3643e34f23e193bc4f1c Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 25 Mar 2018 13:37:33 -0400
Subject: [PATCH] Strips back Vic-20 static analysis to the bare minimum.

Also corrects an unsafe assumption in fast loading.
---
 Analyser/Static/Commodore/StaticAnalyser.cpp | 16 +++---
 Machines/Commodore/Vic-20/Vic20.cpp          | 51 +++++++++++---------
 2 files changed, 36 insertions(+), 31 deletions(-)

diff --git a/Analyser/Static/Commodore/StaticAnalyser.cpp b/Analyser/Static/Commodore/StaticAnalyser.cpp
index c6daba8f6..4ec29a806 100644
--- a/Analyser/Static/Commodore/StaticAnalyser.cpp
+++ b/Analyser/Static/Commodore/StaticAnalyser.cpp
@@ -98,8 +98,8 @@ void Analyser::Static::Commodore::AddTargets(const Media &media, std::vector<std
 		}
 
 		// General approach: increase memory size conservatively such that the largest file found will fit.
-		for(File &file : files) {
-			std::size_t file_size = file.data.size();
+//		for(File &file : files) {
+//			std::size_t file_size = file.data.size();
 //			bool is_basic = file.is_basic();
 
 			/*if(is_basic)
@@ -125,16 +125,16 @@ void Analyser::Static::Commodore::AddTargets(const Media &media, std::vector<std
 				// An unexpanded Vic has memory between 0x0000 and 0x0400; and between 0x1000 and 0x2000.
 				// A 3kb expanded Vic fills in the gap and has memory between 0x0000 and 0x2000.
 				// A 32kb expanded Vic has memory in the entire low 32kb.
-				uint16_t starting_address = file.starting_address;
+//				uint16_t starting_address = file.starting_address;
 
 				// If anything above the 8kb mark is touched, mark as a 32kb machine; otherwise if the
 				// region 0x0400 to 0x1000 is touched and this is an unexpanded machine, mark as 3kb.
-				if(starting_address + file_size > 0x2000)
-					target->memory_model = Target::MemoryModel::ThirtyTwoKB;
-				else if(target->memory_model == Target::MemoryModel::Unexpanded && !(starting_address >= 0x1000 || starting_address+file_size < 0x0400))
-					target->memory_model = Target::MemoryModel::ThirtyTwoKB;
+//				if(starting_address + file_size > 0x2000)
+//					target->memory_model = Target::MemoryModel::ThirtyTwoKB;
+//				else if(target->memory_model == Target::MemoryModel::Unexpanded && !(starting_address >= 0x1000 || starting_address+file_size < 0x0400))
+//					target->memory_model = Target::MemoryModel::ThirtyTwoKB;
 //			}
-		}
+//		}
 	}
 
 	if(!target->media.empty())
diff --git a/Machines/Commodore/Vic-20/Vic20.cpp b/Machines/Commodore/Vic-20/Vic20.cpp
index bb836401b..368fab781 100644
--- a/Machines/Commodore/Vic-20/Vic20.cpp
+++ b/Machines/Commodore/Vic-20/Vic20.cpp
@@ -585,32 +585,37 @@ class ConcreteMachine:
 						uint8_t x = static_cast<uint8_t>(m6502_.get_value_of_register(CPU::MOS6502::Register::X));
 						if(x == 0xe) {
 							Storage::Tape::Commodore::Parser parser;
+							const uint64_t tape_position = tape_->get_tape()->get_offset();
 							std::unique_ptr<Storage::Tape::Commodore::Data> data = parser.get_next_data(tape_->get_tape());
-							uint16_t start_address, end_address;
-							start_address = static_cast<uint16_t>(user_basic_memory_[0xc1] | (user_basic_memory_[0xc2] << 8));
-							end_address = static_cast<uint16_t>(user_basic_memory_[0xae] | (user_basic_memory_[0xaf] << 8));
+							if(data) {
+								uint16_t start_address, end_address;
+								start_address = static_cast<uint16_t>(user_basic_memory_[0xc1] | (user_basic_memory_[0xc2] << 8));
+								end_address = static_cast<uint16_t>(user_basic_memory_[0xae] | (user_basic_memory_[0xaf] << 8));
 
-							// perform a via-processor_write_memory_map_ memcpy
-							uint8_t *data_ptr = data->data.data();
-							std::size_t data_left = data->data.size();
-							while(data_left && start_address != end_address) {
-								uint8_t *page = processor_write_memory_map_[start_address >> 10];
-								if(page) page[start_address & 0x3ff] = *data_ptr;
-								data_ptr++;
-								start_address++;
-								data_left--;
+								// perform a via-processor_write_memory_map_ memcpy
+								uint8_t *data_ptr = data->data.data();
+								std::size_t data_left = data->data.size();
+								while(data_left && start_address != end_address) {
+									uint8_t *page = processor_write_memory_map_[start_address >> 10];
+									if(page) page[start_address & 0x3ff] = *data_ptr;
+									data_ptr++;
+									start_address++;
+									data_left--;
+								}
+
+								// set tape status, carry and flag
+								user_basic_memory_[0x90] |= 0x40;
+								uint8_t	flags = static_cast<uint8_t>(m6502_.get_value_of_register(CPU::MOS6502::Register::Flags));
+								flags &= ~static_cast<uint8_t>((CPU::MOS6502::Flag::Carry | CPU::MOS6502::Flag::Interrupt));
+								m6502_.set_value_of_register(CPU::MOS6502::Register::Flags, flags);
+
+								// to ensure that execution proceeds to 0xfccf, pretend a NOP was here and
+								// ensure that the PC leaps to 0xfccf
+								m6502_.set_value_of_register(CPU::MOS6502::Register::ProgramCounter, 0xfccf);
+								*value = 0xea;	// i.e. NOP implied
+							} else {
+								tape_->get_tape()->set_offset(tape_position);
 							}
-
-							// set tape status, carry and flag
-							user_basic_memory_[0x90] |= 0x40;
-							uint8_t	flags = static_cast<uint8_t>(m6502_.get_value_of_register(CPU::MOS6502::Register::Flags));
-							flags &= ~static_cast<uint8_t>((CPU::MOS6502::Flag::Carry | CPU::MOS6502::Flag::Interrupt));
-							m6502_.set_value_of_register(CPU::MOS6502::Register::Flags, flags);
-
-							// to ensure that execution proceeds to 0xfccf, pretend a NOP was here and
-							// ensure that the PC leaps to 0xfccf
-							m6502_.set_value_of_register(CPU::MOS6502::Register::ProgramCounter, 0xfccf);
-							*value = 0xea;	// i.e. NOP implied
 						}
 					}
 				}