// aud.drc · AudioCodecs · mpddrc::UniDrcSelection · CVE-2026-113912 / 86972
// 原语: OOB 读 · 系统进程 · tier 2
// Primitive: OOB read · system process · tier 2
//
// [zh] MPEG-D DRC 下混矩阵系数校验
// selectDownmixMatrix 在 27.0 仅有零值与相等性检查；矩阵维度直接取自 DRC 元数据，不与系数数组的实际长度比较。27.2 补入三道闸门：nChannels ≤ 8、维度有序、系数数
// == 行×列，并为 getSignalPeakLevel 与 Process 增加计数校验。
//
// [en] MPEG-D DRC downmix matrix coefficient validation
// On 27.0 selectDownmixMatrix has only zero and equality checks; the matrix dimensions come straight
// from DRC metadata and are never compared against the coefficient array's real length. iOS 27.2
// adds three gates — nChannels ≤ 8, ordered dimensions, coefficient count == rows×cols — plus count
// checks in getSignalPeakLevel and Process.
// ── 判别 / oracle ──
// 需要 MPEG-D DRC 元数据的音频文件。应用侧探 AudioCodecs 是否导出这些符号。

import Foundation

// ── byte helpers — verbatim from Cinder27 Sources/Kit.swift ──
enum B {
    static func be16(_ v: UInt16) -> [UInt8] { [UInt8(v >> 8 & 0xff), UInt8(v & 0xff)] }
    static func le16(_ v: UInt16) -> [UInt8] { [UInt8(v & 0xff), UInt8(v >> 8 & 0xff)] }
    static func be32(_ v: UInt32) -> [UInt8] {
        [UInt8(v >> 24 & 0xff), UInt8(v >> 16 & 0xff), UInt8(v >> 8 & 0xff), UInt8(v & 0xff)]
    }
    static func le32(_ v: UInt32) -> [UInt8] {
        [UInt8(v & 0xff), UInt8(v >> 8 & 0xff), UInt8(v >> 16 & 0xff), UInt8(v >> 24 & 0xff)]
    }
    static func be64(_ v: UInt64) -> [UInt8] {
        (0..<8).map { UInt8((v >> (56 - UInt64($0) * 8)) & 0xff) }
    }
    static func le64(_ v: UInt64) -> [UInt8] {
        (0..<8).map { UInt8((v >> (UInt64($0) * 8)) & 0xff) }
    }
    static func both16(_ v: UInt16) -> [UInt8] { le16(v) + be16(v) }
    static func both32(_ v: UInt32) -> [UInt8] { le32(v) + be32(v) }
    static func ascii(_ s: String) -> [UInt8] { Array(s.utf8) }
}