mirror of https://github.com/mre/mos6502.git
95 lines
3.2 KiB
Rust
95 lines
3.2 KiB
Rust
// Copyright (C) 2014 The 6502-rs Developers
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions
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// are met:
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// 1. Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// 2. Redistributions in binary form must reproduce the above copyright
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// notice, this list of conditions and the following disclaimer in the
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// documentation and/or other materials provided with the distribution.
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// 3. Neither the names of the copyright holders nor the names of any
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// contributors may be used to endorse or promote products derived from this
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// software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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// POSSIBILITY OF SUCH DAMAGE.
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use std::ops::Add;
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// The idea here is that it doesn't make sense to add two addresses, but it
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// does make sense to add an address and an "address-difference". (If this
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// is too annoying to work with we should let it go.)
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#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug)]
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pub struct AddressDiff(pub i32);
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#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Debug)]
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pub struct Address(pub u16);
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impl Add<AddressDiff> for Address {
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type Output = Address;
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fn add(self, AddressDiff(rhs): AddressDiff) -> Address {
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let Address(lhs) = self;
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// TODO akeeton: Do a checked cast.
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Address(((lhs as i32) + rhs) as u16)
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}
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}
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impl Add for AddressDiff {
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type Output = AddressDiff;
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fn add(self, AddressDiff(rhs): AddressDiff) -> AddressDiff {
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let AddressDiff(lhs) = self;
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AddressDiff(lhs + rhs)
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}
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}
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#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord)]
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pub struct CheckedAddressDiff(u16);
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impl Add<CheckedAddressDiff> for Address {
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type Output = Address;
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fn add(self, CheckedAddressDiff(rhs): CheckedAddressDiff) -> Address {
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let Address(lhs) = self;
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// We probably don't want to overflow when doing arithmetic in our own
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// code.
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debug_assert!(lhs.checked_add(rhs).is_some());
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Address(lhs + rhs)
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}
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}
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impl Address {
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pub fn to_u16(&self) -> u16 {
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match *self {
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Address(address_) => address_,
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}
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}
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pub fn to_usize(&self) -> usize {
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self.to_u16() as usize
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}
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pub fn get_page_number(&self) -> u8 {
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(self.to_u16() & 0xff00 >> 8) as u8
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}
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pub fn get_offset(&self) -> u8 {
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(self.to_u16() & 0x00ff) as u8
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}
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}
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