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98 lines
3.4 KiB
Rust
98 lines
3.4 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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// 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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#[deriving(PartialEq, Eq, PartialOrd, Ord, Show)]
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pub struct AddressDiff(pub i32);
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#[deriving(PartialEq, Eq, PartialOrd, Ord, Show)]
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pub struct Address(pub u16);
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impl Add<AddressDiff, Address> for 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<AddressDiff, AddressDiff> for 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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// rustc doesn't seem to like having multiple implementations of Add for
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// Address. I believe this is a Rust bug (possibly resolved by "associated
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// types" RFC?). Or I wrote it wrong. Anyway, here's some living dead code:
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/*
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#[deriving(PartialEq, Eq, PartialOrd, Ord)]
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pub struct CheckedAddressDiff(u16);
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impl Add<CheckedAddressDiff, Address> for 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!({
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match lhs.checked_add(&rhs) {
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None => false,
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_ => true
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}
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});
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Address(lhs + rhs)
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}
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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_uint(&self) -> uint {
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self.to_u16() as uint
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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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