[???] Lots of work

Cleanup un-needed elements, simplify memory management

src/emu/ram.rs

@@ -3,14 +3,15 @@ use std::cell::RefCell;
 use crate::emu::mmu::Memory;
 use crate::misc::emulator_error::DeviceType::RAM;
 use crate::misc::emulator_error::EmulatorError;
+use crate::misc::endian::read_big_endian_u24;
 use crate::misc::result::EmulatorResult;
 
 const MAPPED_MEMORY_NOT_REQUIRED: u8 = 8;
-const MEM_LENGTH: usize = (2 << 24) - (MAPPED_MEMORY_NOT_REQUIRED as usize);
 
+pub const MEM_LENGTH: usize = 2 << 23;
 #[derive(Clone, Debug)]
 pub struct RamMemory {
-    data: RefCell<Box<[u8; MEM_LENGTH]>>,
+    pub data: RefCell<Box<[u8; MEM_LENGTH]>>,
 }
 
 impl RamMemory {
@@ -24,6 +25,34 @@ impl RamMemory {
             data: data_refcell
         })
     }
+    pub fn try_from(existing_data:&[u8]) -> EmulatorResult<RamMemory>{
+        let alloc_result = vec![0u8; MEM_LENGTH].into_boxed_slice();
+        // get box of fixed size
+        let mut fixed_size_alloc_box:Box<[u8;MEM_LENGTH]> = alloc_result.try_into().unwrap();
+        fixed_size_alloc_box.copy_from_slice(&existing_data);
+
+        Ok(RamMemory{
+            data: RefCell::new(fixed_size_alloc_box)
+        })
+    }
+
+    pub fn try_get_u24(&self,index:u32)->EmulatorResult<u32>{
+        const U24_LEN:usize = 3;
+        let index_usize = index as usize;
+        let data = self.data.borrow();
+        let a = data.get(index_usize..(index_usize +U24_LEN)).ok_or(EmulatorError::UnreachableMemory(RAM, index))?;
+        Ok(read_big_endian_u24(a.try_into()?))
+    }
+
+    pub fn get_block(&self,address:u32,output:&mut [u8])->EmulatorResult<()>{
+        let address = address as usize;
+        let data = self.data.borrow();
+        let data_requested_slice = data.get(address..address+output.len()).ok_or(EmulatorError::UnreachableMemory(RAM,address as u32))?;
+        output.copy_from_slice(data_requested_slice);
+        Ok(())
+    }
+
+
 }