xmrs 0.10.3

A library to edit SoundTracker data with pleasure
Documentation 
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/// Original XM Module
use bincode::error::DecodeError;
use serde::{Deserialize, Serialize};

use alloc::format;
use alloc::{vec, vec::Vec};

use super::xmheader::{XmFlagType, XmHeader};
use super::xminstrument::XmInstrument;
use super::xmpattern::XmPattern;

use crate::compatibility_profile::CompatibilityProfile;
use crate::import::import_memory::{ImportMemory, MemoryType};
use crate::import::orders_helper;
use crate::import::patternslot::PatternSlot;
use crate::module::Module;
use crate::period_helper::FrequencyType;

#[derive(Default, Serialize, Deserialize, Debug)]
pub struct XmModule {
    pub header: XmHeader,
    pub pattern_order: Vec<u8>,
    pub pattern: Vec<XmPattern>,
    pub instrument: Vec<XmInstrument>,
}

impl XmModule {
    pub fn load(data: &[u8]) -> Result<Self, DecodeError> {
        let (data, header, pattern_order) = XmHeader::load(data)?;
        let mut data = data;

        // Create patterns from xm
        let mut pattern: Vec<XmPattern> = vec![];
        for _i in 0..header.number_of_patterns {
            let (d2, xmp) = XmPattern::load(data, header.number_of_channels)?;
            data = d2;
            pattern.push(xmp);
        }

        // Add empty patterns
        if pattern_order.len() > pattern.len() {
            let empty_ones = pattern_order.len() - pattern.len();
            let empty = XmPattern::new(64, header.number_of_channels.into());
            pattern.extend(core::iter::repeat_n(empty, empty_ones));
        }

        let mut instrument: Vec<XmInstrument> = vec![];
        for _i in 0..header.number_of_instruments {
            // Create instruments form xm
            let (d2, xmi) = XmInstrument::load(data)?;
            data = d2;
            instrument.push(xmi);
        }

        Ok(XmModule {
            header,
            pattern_order,
            pattern,
            instrument,
        })
    }

    pub fn to_module(&self) -> Module {
        // Create module from xm
        let mut module = Module {
            name: self.header.name.clone(),
            comment: format!(
                "{} ({}.{:02})",
                self.header.tracker_name,
                self.header.version_number >> 8,
                self.header.version_number & 0xFF
            ),
            // FT2 canonical replay behaviour — every XM module is
            // authored against these, so the XM importer opts them
            // all on. Editor-authored modules that leave `profile`
            // at default get clean playback without any of these
            // historical edges.
            profile: CompatibilityProfile::ft2(),
            frequency_type: match self.header.flags {
                XmFlagType::XmAmigaFrequencies => FrequencyType::AmigaFrequencies,
                XmFlagType::XmLinearFrequencies => FrequencyType::LinearFrequencies,
            },
            restart_position: self.header.restart_position as usize,
            default_tempo: self.header.default_tempo as usize,
            default_bpm: self.header.default_bpm as usize,
            pattern_order: orders_helper::parse_orders(&self.pattern_order),
            pattern: vec![],
            pattern_names: vec![],
            channel_names: vec![],
            // XM has no per-channel defaults in its header — every
            // channel starts centred and unmuted.
            channel_defaults: vec![],
            instrument: vec![],
            // XM has no MIDI-macro concept — the feature is
            // IT-specific.
            midi_macros: None,
            // XM has no mix-volume byte in its header. Schism
            // (`fmt/xm.c:885`) hard-codes `mixing_volume = 48` for
            // every imported XM, which normalised gives 48/128 =
            // 0.375. We mirror that so the player's mixer chain
            // applies the same headroom for XM as for IT — the same
            // engine-side `MIXING_ATTENUATION` shift expects this
            // pre-attenuation as input.
            mix_volume: 48.0 / 128.0,
        };

        let patterns: Vec<Vec<Vec<PatternSlot>>> =
            self.pattern.iter().map(|p| p.pattern.clone()).collect();
        let mut im = ImportMemory::default();
        module.pattern = im.unpack_patterns(
            module.frequency_type,
            MemoryType::Xm,
            &module.pattern_order,
            &patterns,
        );

        for i in &self.instrument {
            module.instrument.push(i.to_instrument())
        }

        module
    }
}