[ram] Normalize memory access across memory devices

src/emu/ram.rs

@@ -0,0 +1,68 @@
+use std::ops::Index;
+use crate::emu::mmu::Memory;
+use crate::misc::emulator_error::DeviceType::RAM;
+use crate::misc::emulator_error::EmulatorError;
+use crate::misc::result::EmulatorResult;
+
+const MAPPED_MEMORY_NOT_REQUIRED: u8 = 8;
+const MEM_LENGTH: usize = (2 << 24) - (MAPPED_MEMORY_NOT_REQUIRED as usize);
+
+#[derive(Clone, Debug)]
+pub struct RamMemory {
+    data: Box<[u8; MEM_LENGTH]>,
+}
+
+impl RamMemory {
+    pub fn try_new() -> EmulatorResult<RamMemory> {
+        let alloc_result = vec![0; MEM_LENGTH].into_boxed_slice();
+        let data = alloc_result.try_into().map_err(|err|{
+            EmulatorError::AllocationFailure(RAM, "Allocation failed")
+        })?;
+        Ok(RamMemory {
+            data
+        })
+    }
+}
+
+
+impl Memory for RamMemory {
+    fn try_get_byte(&self, address: u32) -> EmulatorResult<u8> {
+        log::trace!("Fetch RAM memory at address {}",address);
+        let x = *self.data.get(address as usize).ok_or(EmulatorError::UnreachableMemory(RAM, address))?;
+        Ok(x)
+    }
+
+    fn try_set_byte(&mut self, address: u32, value: u8) -> EmulatorResult<()> {
+        if address>= MEM_LENGTH as u32 {
+            return Err(EmulatorError::UnreachableMemory(RAM, address))
+        }
+        self.data[address as usize] = value;
+        Ok(())
+    }
+}
+
+
+
+
+#[cfg(test)]
+mod tests{
+    use crate::emu::ram::RamMemory;
+    use crate::emu::mmu::Memory;
+    const EXAMPLE_ADDRESS:u32=0x24;
+
+    #[test]
+    pub fn get_mem(){
+        let ram_result = RamMemory::try_new();
+        assert!(ram_result.is_ok())
+    }
+    #[test]
+    pub fn get_set_memory(){
+        const EXAMPLE_DATA:u8 = 0xa5;
+        let mut ram = RamMemory::try_new().unwrap();
+        let byte_before = ram.try_get_byte(EXAMPLE_ADDRESS).unwrap();
+        ram.try_set_byte(EXAMPLE_ADDRESS, EXAMPLE_DATA).unwrap();
+        let byte_after = ram.try_get_byte(EXAMPLE_ADDRESS).unwrap();
+        assert_eq!(0,byte_before);
+        assert_eq!(EXAMPLE_DATA,byte_after);
+    }
+}