mirror of https://github.com/mre/mos6502.git
112 lines
3.6 KiB
Rust
112 lines
3.6 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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// JAM: We can probably come up with a better way to represent address ranges.
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// Address range type?
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//
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// // Address range -- inclusive on both sides
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// pub struct AddressRangeIncl {
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// begin: Address,
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// end: Address,
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// }
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const ADDR_LO_BARE: u16 = 0x0000;
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const ADDR_HI_BARE: u16 = 0xFFFF;
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pub const MEMORY_ADDRESS_LO: u16 = ADDR_LO_BARE;
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pub const MEMORY_ADDRESS_HI: u16 = ADDR_HI_BARE;
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pub const STACK_ADDRESS_LO: u16 = 0x0100;
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pub const STACK_ADDRESS_HI: u16 = 0x01FF;
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pub const IRQ_INTERRUPT_VECTOR_LO: u16 = 0xFFFE;
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pub const IRQ_INTERRUPT_VECTOR_HI: u16 = 0xFFFF;
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const MEMORY_SIZE: usize = (ADDR_HI_BARE - ADDR_LO_BARE) as usize + 1usize;
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// FIXME: Should this use indirection for `bytes`?
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#[derive(Copy, Clone)]
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pub struct Memory {
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bytes: [u8; MEMORY_SIZE],
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}
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impl Default for Memory {
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fn default() -> Self {
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Self::new()
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}
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}
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pub trait Bus {
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fn get_byte(&self, address: u16) -> u8;
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fn set_byte(&mut self, address: u16, value: u8);
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fn set_bytes(&mut self, start: u16, values: &[u8]) {
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for i in 0..values.len() as u16 {
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self.set_byte(start + i, values[i as usize]);
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}
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}
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}
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impl Memory {
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pub fn new() -> Memory {
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Memory {
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bytes: [0; MEMORY_SIZE],
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}
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}
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}
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impl Bus for Memory {
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fn get_byte(&self, address: u16) -> u8 {
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self.bytes[address as usize]
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}
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// Sets the byte at the given address to the given value and returns the
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// previous value at the address.
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fn set_byte(&mut self, address: u16, value: u8) {
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self.bytes[address as usize] = value;
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}
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fn set_bytes(&mut self, start: u16, values: &[u8]) {
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let start = start as usize;
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// This panics if the range is invalid
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let end = start + values.len();
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self.bytes[start..end].copy_from_slice(values);
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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#[should_panic]
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fn test_memory_overflow_panic() {
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let mut memory = Memory::new();
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memory.set_bytes(0xFFFE, &[1, 2, 3]);
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}
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}
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