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48 lines
1.4 KiB
C++
48 lines
1.4 KiB
C++
//
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// File.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 10/09/2016.
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// Copyright 2016 Thomas Harte. All rights reserved.
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//
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#include "File.hpp"
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bool Analyser::Static::Commodore::File::is_basic() {
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// BASIC files are always relocatable (?)
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if(type != File::RelocatableProgram) return false;
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uint16_t line_address = starting_address;
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int line_number = -1;
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// decide whether this is a BASIC file based on the proposition that:
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// (1) they're always relocatable; and
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// (2) they have a per-line structure of:
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// [4 bytes: address of start of next line]
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// [4 bytes: this line number]
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// ... null-terminated code ...
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// (with a next line address of 0000 indicating end of program)
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while(1) {
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if(size_t(line_address - starting_address) >= data.size() + 2) break;
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uint16_t next_line_address = data[line_address - starting_address];
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next_line_address |= data[line_address - starting_address + 1] << 8;
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if(!next_line_address) {
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return true;
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}
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if(next_line_address < line_address + 5) break;
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if(size_t(line_address - starting_address) >= data.size() + 5) break;
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uint16_t next_line_number = data[line_address - starting_address + 2];
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next_line_number |= data[line_address - starting_address + 3] << 8;
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if(next_line_number <= line_number) break;
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line_number = uint16_t(next_line_number);
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line_address = next_line_address;
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}
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return false;
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}
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