[mem] Add mapped memory

src/emu/endian.rs

@@ -0,0 +1,15 @@
+
+/// read a 24bit endian value, and place it in a u32 num
+pub fn read_big_endian_tribyte(input:&[u8;3]) ->u32{
+    todo!()
+}
+
+pub fn read_big_endian_byte_array(input:&[u8]) ->u32{
+    todo!()
+}
+
+
+/// Get 24 bit big endian slice
+pub fn get_big_endian(input:u32)->[u8;3]{
+    todo!()
+}

src/emu/iomem.rs

@@ -0,0 +1,60 @@
+
+use crate::emu::mmu::Memory;
+
+#[derive(Debug, Copy, Clone)]
+pub struct MemoryMappedIO {
+    keyboard_bits: [u8;2],
+    program_counter: [u8; 3],
+    pixel_reg: u8,
+    audio_sample_address_base: [u8; 2],
+}
+
+impl MemoryMappedIO {
+    pub fn new() -> MemoryMappedIO {
+        MemoryMappedIO {
+            keyboard_bits: [0,0],
+            program_counter: [0, 0, 0],
+            pixel_reg: 0,
+            audio_sample_address_base: [0, 0],
+        }
+    }
+}
+
+const KEYBOARD_BIT_START: u32 = 0;
+const KEYBOARD_BIT_END: u32 = 1;
+const PC_START_ADDR: u32 = 2;
+const PC_LEN: u32 = 3;
+const PC_END_ADDR: u32 = PC_START_ADDR + PC_LEN - 1;
+
+const PIXEL_BASE: u32 = 5;
+const AUDIO_SAMPLE_BASE_START: u32 = 6;
+const AUDIO_SAMPLE_BASE_LEN: u32 = 2;
+const AUDIO_SAMPLE_BASE_END: u32 = AUDIO_SAMPLE_BASE_START + AUDIO_SAMPLE_BASE_LEN - 1;
+
+impl Memory for MemoryMappedIO {
+    fn get_byte(&self, address: u32) -> u8 {
+        match address {
+            KEYBOARD_BIT_START..=KEYBOARD_BIT_END => {
+                let addr_usize = address as usize;
+                log::trace!("Fetching keyboard bits segment {}",addr_usize);
+                self.keyboard_bits[addr_usize]
+            },
+            PC_START_ADDR..=PC_END_ADDR => {
+                let pc_index = (address - PC_START_ADDR) as usize;
+                log::trace!("Fetching PC {:?} bit segment {}",self.program_counter,pc_index);
+                self.program_counter[pc_index]
+            },
+            PIXEL_BASE => {
+                log::trace!("Fetching pixel base reg {}",self.pixel_reg);
+                self.pixel_reg
+            },
+            AUDIO_SAMPLE_BASE_START => self.audio_sample_address_base[0],
+            AUDIO_SAMPLE_BASE_END => self.audio_sample_address_base[1],
+            _ => { panic!("Unreachable code") }
+        }
+    }
+
+    fn set_byte(&mut self, address: u32, val: u8) {
+        todo!()
+    }
+}

src/emu/mem.rs

@@ -0,0 +1,28 @@
+use crate::emu::mmu::Memory;
+
+const MEM_LENGTH: usize = 2 << 24;
+
+#[derive(Clone, Debug)]
+pub struct RamMemory {
+    data: Box<[u8; MEM_LENGTH]>,
+}
+
+impl RamMemory {
+    pub fn new() -> RamMemory {
+        RamMemory {
+            data: vec![0; MEM_LENGTH].into_boxed_slice().try_into().expect("Incorrect ram allocation")
+        }
+    }
+}
+
+impl Memory for RamMemory {
+    fn get_byte(&self, address: u32) -> u8 {
+        log::trace!("Fetch RAM memory at address {}",address);
+        let x = *self.data.get(address as usize).expect("Unchecked address fetch");
+        x
+    }
+
+    fn set_byte(&mut self, address: u32, val: u8) {
+        self.data[address as usize] = val;
+    }
+}

src/emu/mmu.rs

@@ -0,0 +1,46 @@
+use crate::emu::iomem::MemoryMappedIO;
+use crate::emu::mem::RamMemory;
+
+pub const MMAPPEDIO_END: u32 = RAM_MEM_START-1;
+pub const RAM_MEM_START:u32 = 8;
+pub const RAM_MEM_END: u32 = 2<<24 - 1;
+
+///
+/// mapped I/O + RAM.
+pub trait Memory {
+    /// Get the value (24bit) at the address(24bit)
+    fn get_byte(&self, address: u32) -> u8;
+    /// Set the value at the 24bit address
+    fn set_byte(&mut self, address: u32, value: u8);
+}
+#[derive(Debug,Clone)]
+pub struct MappedMemory {
+    memory_mapped_io: MemoryMappedIO,
+    ram_memory: RamMemory,
+}
+impl MappedMemory {
+    pub fn new(memory_mapped_io: MemoryMappedIO, ram_memory: RamMemory)-> MappedMemory {
+        MappedMemory {
+            memory_mapped_io,
+            ram_memory
+        }
+    }
+}
+
+impl Memory for MappedMemory {
+    fn get_byte(&self, address: u32) -> u8 {
+        match address {
+            0..=MMAPPEDIO_END => {
+                self.memory_mapped_io.get_byte(address)
+            },
+            RAM_MEM_START..=RAM_MEM_END =>{
+                self.ram_memory.get_byte(address)
+            }
+            _ => { panic!("Invalid address") }
+        }
+    }
+    fn set_byte(&mut self, address: u32, value: u8) {
+        todo!()
+    }
+}
+

src/emu/mod.rs

@@ -0,0 +1,5 @@
+pub mod cpu;
+pub mod mmu;
+pub mod mem;
+mod endian;
+pub mod iomem;