Sylpheed/crates/sylpheed-formats/examples/blend_vs_t8ad_bit.rs

//! Does `T8aD +0x04` bit `0x02` predict the blend the GAME uses?
//!
//! ⚠️ **`REFUTED.md` kills this claim**: *"`T8aD +0x04` bit `0x02` selects an
//! additive blend" → mine, and refuted. Blending those sprites additively
//! worsens every measure against the capture.* That refutation rests entirely on
//! **our renderer** — it is a claim about our renderer, and the corpus's own rule
//! says so. Since it was written, the blend has been measured off the GPU per
//! draw on three screens (`structures/ui-blend-mode-measured.md`), so the claim
//! can now be tested against the oracle instead of against a render.
//!
//! The labels below are **not** from a render. Every one is a
//! `RB_BLENDCONTROL0` value read out of the guest command stream and attributed
//! to an element by quad size:
//!   `data/ui-blend-mode-measured.txt`, `data/ui-blend-title-and-replication.txt`,
//!   `data/ui-blend-extras-complete.txt`.
//!
//!     cargo run -p sylpheed-formats --example blend_vs_t8ad_bit
use std::collections::BTreeMap;
use std::path::PathBuf;
use sylpheed_formats::{pak::PakArchive, ui_layout};

/// (build entry, sprite, measured additive?) — the oracle's verdicts, verbatim.
const MEASURED: &[(usize, &str, bool)] = &[
    // --- GP_TITLE entry 4 + 2, the live title -------------------------------
    (4, "ptbase2.t32", false),
    (4, "ptlogo1.t32", false),
    (4, "ptlogo2.t32", false),
    (4, "ptlogo_tm.t32", false),
    (4, "ptcopyright.t32", false),
    (4, "ptlogo_back2.t32", false),
    (4, "ptlogo_back2eff.t32", false),
    (2, "ptbtn00.t32", false),
    (2, "ptbtn00f.t32", true),
    // --- entry 5, the main menu ---------------------------------------------
    (5, "ptbase.t32", false),
    (5, "ptmsg.t32", false),
    (5, "ptbtn01f.t32", false),
    (5, "ptbtneff01.t32", false),
    (5, "pteff10.t32", true),
    (5, "pteff12.t32", true),
    (5, "ptframe1.t32", true),
    (5, "ptframe2.t32", true),
    (5, "pteff03.t32", true), // the rotated sweep strips, via ptloop01/02
    (5, "pteff03a.t32", true),
    // --- entry 6, EXTRAS ------------------------------------------------------
    (6, "ptbase.t32", false),
    (6, "ptmsg2.t32", false),
    (6, "pttitle.t32", false),
    (6, "ptbtn11f.t32", false),
    (6, "ptbtn12.t32", false),
    (6, "ptbtn13.t32", false),
    (6, "ptbtneff02.t32", false),
    (6, "pteff10.t32", true),
    (6, "pteff20.t32", true),
    (6, "pteff21.t32", true),
    (6, "pteff22.t32", true),
    (6, "pteff23.t32", true),
    (6, "ptframe3.t32", true),
    (6, "ptframe4.t32", true),
    (6, "pteff03.t32", true),
    (6, "pteff03a.t32", true),
];

fn main() {
    if std::env::args().any(|a| a == "decl") {
        decl_rivals();
        return;
    }
    let root = PathBuf::from(std::env::var("SYLPHEED_DISC").expect("SYLPHEED_DISC"));
    let ar = PakArchive::open(root.join("dat/GP_TITLE.pak")).expect("GP_TITLE");
    let mut hdr: BTreeMap<(usize, String), u32> = BTreeMap::new();
    for e in [2usize, 4, 5, 6] {
        let by = ar.read(&ar.entries()[e]).expect("entry");
        let b = ui_layout::parse_build(&by).expect("build");
        for (n, &(off, size)) in &b.sprites {
            let s = &by[off..(off + size).min(by.len())];
            if s.len() < 8 || &s[0..4] != b"T8aD" {
                continue;
            }
            hdr.insert((e, n.clone()), u32::from_be_bytes([s[4], s[5], s[6], s[7]]));
        }
    }
    println!(
        "{:<10} {:<22} {:<10} {:>10}  measured blend",
        "entry", "sprite", "+0x04", "bit 0x02"
    );
    let (mut tp, mut tn, mut fp, mut fnn, mut missing) = (0, 0, 0, 0, 0);
    for &(e, n, additive) in MEASURED {
        let Some(&w) = hdr.get(&(e, n.to_string())) else {
            println!(
                "{e:<10} {n:<22} {:<10} {:>10}  {}",
                "MISSING",
                "-",
                if additive { "ADDITIVE" } else { "alpha-over" }
            );
            missing += 1;
            continue;
        };
        let bit = w & 0x02 != 0;
        match (bit, additive) {
            (true, true) => tp += 1,
            (false, false) => tn += 1,
            (true, false) => fp += 1,
            (false, true) => fnn += 1,
        }
        println!(
            "{e:<10} {n:<22} {:08X}   {:>10}  {}{}",
            w,
            bit,
            if additive { "ADDITIVE" } else { "alpha-over" },
            if bit == additive {
                ""
            } else {
                "   <== DISAGREES"
            }
        );
    }
    println!("\nbit set & additive      {tp}");
    println!("bit clear & alpha-over  {tn}");
    println!("bit set & alpha-over    {fp}   <- false positives");
    println!("bit clear & additive    {fnn}   <- false negatives");
    println!("sprite not found        {missing}");
    println!(
        "\n{}",
        if fp == 0 && fnn == 0 && missing == 0 {
            "PERFECT PARTITION on every element whose blend was measured."
        } else {
            "THE BIT DOES NOT PREDICT THE MEASURED BLEND."
        }
    );

    // ── THE CONTROL THAT MATTERS ────────────────────────────────────────────
    // A perfect partition is worthless if half the header partitions equally
    // well: then the sample is too small to single out a field, and picking
    // `+0x04` bit 0x02 out of the tie is the same mistake as picking `+0x08`
    // 0x8050 was. So: how many OTHER bits of the first 12 header words separate
    // the same 35 elements without error?
    let mut rivals: Vec<String> = Vec::new();
    let mut words: BTreeMap<(usize, String), Vec<u32>> = BTreeMap::new();
    for e in [2usize, 4, 5, 6] {
        let by = ar.read(&ar.entries()[e]).expect("entry");
        let b = ui_layout::parse_build(&by).expect("build");
        for (n, &(off, size)) in &b.sprites {
            let s = &by[off..(off + size).min(by.len())];
            if s.len() < 48 || &s[0..4] != b"T8aD" {
                continue;
            }
            words.insert(
                (e, n.clone()),
                (0..12)
                    .map(|k| {
                        u32::from_be_bytes([s[k * 4], s[k * 4 + 1], s[k * 4 + 2], s[k * 4 + 3]])
                    })
                    .collect(),
            );
        }
    }
    for w in 0..12 {
        for bit in 0..32 {
            let mut ok = true;
            let mut set_seen = false;
            let mut clear_seen = false;
            for &(e, n, additive) in MEASURED {
                let Some(v) = words.get(&(e, n.to_string())) else {
                    ok = false;
                    break;
                };
                let on = (v[w] >> bit) & 1 == 1;
                if on {
                    set_seen = true
                } else {
                    clear_seen = true
                }
                if on != additive {
                    ok = false;
                    break;
                }
            }
            // A constant bit trivially "agrees" with nothing; require both sides.
            if ok && set_seen && clear_seen {
                rivals.push(format!("+0x{:02X} bit {bit} (0x{:X})", w * 4, 1u32 << bit));
            }
        }
    }
    println!("\nRIVAL FIELDS — other bits of the first 12 header words that separate");
    println!("the same 35 elements with zero errors: {}", rivals.len());
    for r in &rivals {
        println!("   {r}");
    }
    if rivals.len() == 1 {
        println!("   -> the sample singles out ONE field. Nothing else in the header does it.");
    } else {
        println!(
            "   -> the sample does NOT single out a field; {} candidates tie.",
            rivals.len()
        );
    }
}

// ── An integrity check the published decode did NOT do ──────────────────────
// The rival sweep above covers the 48-byte T8aD header. It does NOT cover the
// 60-byte DECLARATION entry, and the earlier declaration hunt was run with
// labels taken from the port's RENDER -- which put pteff10, pteff12, pteff20 and
// pteff21..23 on the alpha-over side, where the oracle says all six are
// additive. So the declaration has never been swept with correct labels, and if
// one of its words also partitions the 35 without error, "the field is the T8aD
// bit" is underdetermined.
//
// Run as:  cargo run -p sylpheed-formats --example blend_vs_t8ad_bit -- decl
#[allow(dead_code)]
fn decl_rivals() {
    use std::collections::BTreeMap;
    let root = PathBuf::from(std::env::var("SYLPHEED_DISC").expect("SYLPHEED_DISC"));
    let ar = PakArchive::open(root.join("dat/GP_TITLE.pak")).expect("GP_TITLE");
    const AT: usize = 0x20;
    const STRIDE: usize = 60;
    let mut decl: BTreeMap<(usize, String), Vec<u32>> = BTreeMap::new();
    for e in [2usize, 4, 5, 6] {
        let Ok(by) = ar.read(&ar.entries()[e]) else {
            continue;
        };
        if by.len() < 0x18 {
            continue;
        }
        let count = u32::from_be_bytes([by[0x14], by[0x15], by[0x16], by[0x17]]) as usize;
        for i in 0..count {
            let at = AT + i * STRIDE;
            if at + STRIDE > by.len() {
                break;
            }
            let end = by[at..at + 12].iter().position(|&c| c == 0).unwrap_or(12);
            let name = String::from_utf8_lossy(&by[at..at + end]).to_string();
            decl.insert(
                (e, name),
                (0..15)
                    .map(|k| {
                        u32::from_be_bytes([
                            by[at + k * 4],
                            by[at + k * 4 + 1],
                            by[at + k * 4 + 2],
                            by[at + k * 4 + 3],
                        ])
                    })
                    .collect(),
            );
        }
    }
    let mut missing: Vec<String> = Vec::new();
    for &(e, n, _) in MEASURED {
        if !decl.contains_key(&(e, n.to_string())) {
            missing.push(format!("entry {e} {n}"));
        }
    }
    println!("\n=== DECLARATION-ENTRY RIVAL SWEEP ===");
    println!(
        "measured elements with NO declaration entry of their own: {} of {}",
        missing.len(),
        MEASURED.len()
    );
    for m in &missing {
        println!("   {m}");
    }
    if !missing.is_empty() {
        println!("   -> no declaration field can select the blend for these, because they");
        println!("      have no declaration entry. The header is the only per-sprite home.");
    }
    let labelled: Vec<&(usize, &str, bool)> = MEASURED
        .iter()
        .filter(|(e, n, _)| decl.contains_key(&(*e, n.to_string())))
        .collect();
    let mut rivals = 0;
    #[allow(clippy::needless_range_loop)]
    for w in 0..15 {
        for bit in 0..32 {
            let (mut ok, mut s, mut c) = (true, false, false);
            for &&(e, n, additive) in &labelled {
                let on = (decl[&(e, n.to_string())][w] >> bit) & 1 == 1;
                if on {
                    s = true
                } else {
                    c = true
                }
                if on != additive {
                    ok = false;
                    break;
                }
            }
            if ok && s && c {
                println!("   RIVAL: declaration +0x{:02X} bit {bit}", w * 4);
                rivals += 1;
            }
        }
    }
    println!(
        "declaration bits that separate the {} labellable elements: {rivals}",
        labelled.len()
    );
}