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/*
Copyright (C) 2020-2022 Rafal Michalski
This file is part of SPECTRUSTY, a Rust library for building emulators.
For the full copyright notice, see the lib.rs file.
*/
/*! **SCR** file format utilities.
Utilities in this module can work with the ULAplus extensions to the **SCR** format:
The type of the file is recognized by its total byte size:
| size | description |
|-------|-----------------------------------------------------------------------------------------|
| 6912 | Standard screen data. |
| 6976 | Standard screen data + 64 palette registers. |
| 12288 | Hi-color screen data as primary screen data followed by the secondary screen data. |
| 12352 | Hi-color screen data + 64 palette registers. |
| 12289 | Hi-res screen data (primary + secondary) followed by the hi-res color information byte. |
| 12353 | Hi-res screen data (primary + secondary + hi-res color) + 64 palette registers. |
*/
use core::slice;
use std::io::{self, Read, Write, Seek, SeekFrom};
pub use spectrusty_core::memory::ScreenArray;
const PIXELS_SIZE: usize = 6144;
const SCR_SIZE: u64 = 6912;
const PALETTE_SIZE: u64 = 64;
const SCR_PLUS_SIZE: u64 = SCR_SIZE + PALETTE_SIZE;
const SCR_HICOLOR_SIZE: u64 = PIXELS_SIZE as u64 * 2;
const SCR_HICOLOR_PLUS_SIZE: u64 = SCR_HICOLOR_SIZE + PALETTE_SIZE;
const SCR_HIRES_SIZE: u64 = SCR_HICOLOR_SIZE + 1;
const SCR_HIRES_PLUS_SIZE: u64 = SCR_HICOLOR_SIZE + 1 + PALETTE_SIZE;
/// This enum indicates a current or requested screen mode.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum ScrMode {
/// The default ULA screen mode.
/// The `bool` should be `true` if the ULAplus palette is or should be supported. Otherwise it's `false`.
Classic(bool),
/// The high color SCLD screen mode.
/// The `bool` should be `true` if the ULAplus palette is or should be supported. Otherwise it's `false`.
HighColor(bool),
/// The high resultion SCLD screen mode.
/// The `u8` is a high resolution color scheme on bits 3 to 5.
/// The `bool` should be `true` if the ULAplus palette is or should be supported. Otherwise it's `false`.
HighRes(u8, bool),
}
/// Utilities for loading and saving **SCR** files.
///
/// Methods of this trait are implemented automatically for types that implement [ScreenDataProvider].
pub trait LoadScr: ScreenDataProvider {
/// Attempts to read the `SCR` file from the `src` and load it into the underlying implementation.
///
/// # Errors
/// This function will return an error if a file is not recognized as an `SCR` file
/// or the requested screen mode exceeds the capacity of the underlying implementation.
/// Other errors may also be returned from attempts to read the file.
fn load_scr<R: Read + Seek>(&mut self, scr: R) -> io::Result<()>;
/// Attempts to save the screen from the underlying implementation and write as the `SCR`
/// file into the `dst`.
///
/// # Errors
/// This function may return an error from attempts to write the file.
fn save_scr<W: Write>(&self, dst: W) -> io::Result<()>;
}
/// This trait should be implemented by the core chipset emulator types.
pub trait ScreenDataProvider {
/// Should return a currently selected screen mode.
fn get_screen_mode(&self) -> ScrMode;
/// Should set a requested screen `mode` and return `true`.
/// If the provided `mode` can not be set this method should return `false`.
fn set_screen_mode(&mut self, mode: ScrMode) -> bool;
/// Should return a reference to the primary screen data.
fn screen_primary_ref(&self) -> &ScreenArray;
/// Should return a mutable reference to the primary screen data.
fn screen_primary_mut(&mut self) -> &mut ScreenArray;
/// Should return a reference to the secondary screen data.
///
/// # Panics
/// This method may panic if the secondary screen is not supported by the underlying implementation.
fn screen_secondary_ref(&self) -> &ScreenArray {
unimplemented!()
}
/// Should return a mutable reference to the secondary screen data.
///
/// # Panics
/// This method may panic if the secondary screen is not supported by the underlying implementation.
fn screen_secondary_mut(&mut self) -> &mut ScreenArray {
unimplemented!()
}
/// Should return a reference to the ULAplus palette.
///
/// # Panics
/// This method may panic if ULAplus is not supported by the underlying implementation.
fn screen_palette_ref(&self) -> &[u8;PALETTE_SIZE as usize] {
unimplemented!()
}
/// Should return a mutable reference to the ULAplus palette.
///
/// # Panics
/// This method may panic if ULAplus is not supported by the underlying implementation.
fn screen_palette_mut(&mut self) -> &mut [u8;PALETTE_SIZE as usize] {
unimplemented!()
}
}
impl<T> LoadScr for T where T: ScreenDataProvider {
fn load_scr<R: Read + Seek>(&mut self, mut src: R) -> io::Result<()> {
let end = src.seek(SeekFrom::End(0))?;
let mode = match end {
SCR_SIZE => ScrMode::Classic(false),
SCR_PLUS_SIZE => ScrMode::Classic(true),
SCR_HICOLOR_SIZE => ScrMode::HighColor(false),
SCR_HICOLOR_PLUS_SIZE => ScrMode::HighColor(true),
SCR_HIRES_SIZE|SCR_HIRES_PLUS_SIZE => {
src.seek(SeekFrom::Current(
if end == SCR_HIRES_PLUS_SIZE {
-(PALETTE_SIZE as i64) - 1
}
else {
-1
}
))?;
let mut color: u8 = 0;
src.read_exact(slice::from_mut(&mut color))?;
ScrMode::HighRes(color, end == SCR_HIRES_PLUS_SIZE)
}
_ => {
return Err(io::Error::new(io::ErrorKind::InvalidData, "Screen format not recognized"));
}
};
if !self.set_screen_mode(mode) {
return Err(io::Error::new(io::ErrorKind::InvalidInput, "Screen format not supported"));
}
src.seek(SeekFrom::Start(0))?;
match end {
SCR_SIZE|SCR_PLUS_SIZE => {
src.read_exact(self.screen_primary_mut())?;
}
SCR_HICOLOR_SIZE|SCR_HICOLOR_PLUS_SIZE|
SCR_HIRES_SIZE|SCR_HIRES_PLUS_SIZE => {
src.read_exact(&mut self.screen_primary_mut()[0..PIXELS_SIZE])?;
src.read_exact(&mut self.screen_secondary_mut()[0..PIXELS_SIZE])?;
}
_ => {}
}
if let SCR_PLUS_SIZE|SCR_HICOLOR_PLUS_SIZE|SCR_HIRES_PLUS_SIZE = end {
src.seek(SeekFrom::Start(end - PALETTE_SIZE))?;
src.read_exact(self.screen_palette_mut())?;
}
Ok(())
}
fn save_scr<W: Write>(&self, mut dst: W) -> io::Result<()> {
let mode = self.get_screen_mode();
match mode {
ScrMode::Classic(..) => dst.write_all(self.screen_primary_ref())?,
ScrMode::HighColor(..)|ScrMode::HighRes(..) => {
dst.write_all(&self.screen_primary_ref()[0..PIXELS_SIZE])?;
dst.write_all(&self.screen_secondary_ref()[0..PIXELS_SIZE])?;
}
}
if let ScrMode::HighRes(outmode, ..) = mode {
dst.write_all(slice::from_ref(&outmode))?;
}
if let ScrMode::Classic(true)|
ScrMode::HighColor(true)|
ScrMode::HighRes(.., true) = mode {
dst.write_all(self.screen_palette_ref())?;
}
Ok(())
}
}