cridecoder 0.2.2

//! IMDCT (Inverse Modified Discrete Cosine Transform) for HCA decoding

use super::decoder::{StChannel, HCA_SAMPLES_PER_SUBFRAME};
use super::tables::IMDCT_WINDOW;

const HALF: usize = HCA_SAMPLES_PER_SUBFRAME / 2;

const fn table_from_bits(hex: [[u32; 64]; 7]) -> [[f32; 64]; 7] {
    let mut result = [[0.0f32; 64]; 7];
    let mut i = 0;
    while i < 7 {
        let mut j = 0;
        while j < 64 {
            result[i][j] = f32::from_bits(hex[i][j]);
            j += 1;
        }
        i += 1;
    }
    result
}

/// Sin tables for DCT-IV (7 x 64 arrays)
static SIN_TABLES: [[f32; 64]; 7] = table_from_bits([
    [
        0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75,
        0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75,
        0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75,
        0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75,
        0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75,
        0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75,
        0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75,
        0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75,
        0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75, 0x3DA73D75,
        0x3DA73D75,
    ],
    [
        0x3F7B14BE, 0x3F54DB31, 0x3F7B14BE, 0x3F54DB31, 0x3F7B14BE, 0x3F54DB31, 0x3F7B14BE,
        0x3F54DB31, 0x3F7B14BE, 0x3F54DB31, 0x3F7B14BE, 0x3F54DB31, 0x3F7B14BE, 0x3F54DB31,
        0x3F7B14BE, 0x3F54DB31, 0x3F7B14BE, 0x3F54DB31, 0x3F7B14BE, 0x3F54DB31, 0x3F7B14BE,
        0x3F54DB31, 0x3F7B14BE, 0x3F54DB31, 0x3F7B14BE, 0x3F54DB31, 0x3F7B14BE, 0x3F54DB31,
        0x3F7B14BE, 0x3F54DB31, 0x3F7B14BE, 0x3F54DB31, 0x3F7B14BE, 0x3F54DB31, 0x3F7B14BE,
        0x3F54DB31, 0x3F7B14BE, 0x3F54DB31, 0x3F7B14BE, 0x3F54DB31, 0x3F7B14BE, 0x3F54DB31,
        0x3F7B14BE, 0x3F54DB31, 0x3F7B14BE, 0x3F54DB31, 0x3F7B14BE, 0x3F54DB31, 0x3F7B14BE,
        0x3F54DB31, 0x3F7B14BE, 0x3F54DB31, 0x3F7B14BE, 0x3F54DB31, 0x3F7B14BE, 0x3F54DB31,
        0x3F7B14BE, 0x3F54DB31, 0x3F7B14BE, 0x3F54DB31, 0x3F7B14BE, 0x3F54DB31, 0x3F7B14BE,
        0x3F54DB31,
    ],
    [
        0x3F7EC46D, 0x3F74FA0B, 0x3F61C598, 0x3F45E403, 0x3F7EC46D, 0x3F74FA0B, 0x3F61C598,
        0x3F45E403, 0x3F7EC46D, 0x3F74FA0B, 0x3F61C598, 0x3F45E403, 0x3F7EC46D, 0x3F74FA0B,
        0x3F61C598, 0x3F45E403, 0x3F7EC46D, 0x3F74FA0B, 0x3F61C598, 0x3F45E403, 0x3F7EC46D,
        0x3F74FA0B, 0x3F61C598, 0x3F45E403, 0x3F7EC46D, 0x3F74FA0B, 0x3F61C598, 0x3F45E403,
        0x3F7EC46D, 0x3F74FA0B, 0x3F61C598, 0x3F45E403, 0x3F7EC46D, 0x3F74FA0B, 0x3F61C598,
        0x3F45E403, 0x3F7EC46D, 0x3F74FA0B, 0x3F61C598, 0x3F45E403, 0x3F7EC46D, 0x3F74FA0B,
        0x3F61C598, 0x3F45E403, 0x3F7EC46D, 0x3F74FA0B, 0x3F61C598, 0x3F45E403, 0x3F7EC46D,
        0x3F74FA0B, 0x3F61C598, 0x3F45E403, 0x3F7EC46D, 0x3F74FA0B, 0x3F61C598, 0x3F45E403,
        0x3F7EC46D, 0x3F74FA0B, 0x3F61C598, 0x3F45E403, 0x3F7EC46D, 0x3F74FA0B, 0x3F61C598,
        0x3F45E403,
    ],
    [
        0x3F7FB10F, 0x3F7D3AAC, 0x3F7853F8, 0x3F710908, 0x3F676BD8, 0x3F5B941A, 0x3F4D9F02,
        0x3F3DAEF9, 0x3F7FB10F, 0x3F7D3AAC, 0x3F7853F8, 0x3F710908, 0x3F676BD8, 0x3F5B941A,
        0x3F4D9F02, 0x3F3DAEF9, 0x3F7FB10F, 0x3F7D3AAC, 0x3F7853F8, 0x3F710908, 0x3F676BD8,
        0x3F5B941A, 0x3F4D9F02, 0x3F3DAEF9, 0x3F7FB10F, 0x3F7D3AAC, 0x3F7853F8, 0x3F710908,
        0x3F676BD8, 0x3F5B941A, 0x3F4D9F02, 0x3F3DAEF9, 0x3F7FB10F, 0x3F7D3AAC, 0x3F7853F8,
        0x3F710908, 0x3F676BD8, 0x3F5B941A, 0x3F4D9F02, 0x3F3DAEF9, 0x3F7FB10F, 0x3F7D3AAC,
        0x3F7853F8, 0x3F710908, 0x3F676BD8, 0x3F5B941A, 0x3F4D9F02, 0x3F3DAEF9, 0x3F7FB10F,
        0x3F7D3AAC, 0x3F7853F8, 0x3F710908, 0x3F676BD8, 0x3F5B941A, 0x3F4D9F02, 0x3F3DAEF9,
        0x3F7FB10F, 0x3F7D3AAC, 0x3F7853F8, 0x3F710908, 0x3F676BD8, 0x3F5B941A, 0x3F4D9F02,
        0x3F3DAEF9,
    ],
    [
        0x3F7FEC43, 0x3F7F4E6D, 0x3F7E1324, 0x3F7C3B28, 0x3F79C79D, 0x3F76BA07, 0x3F731447,
        0x3F6ED89E, 0x3F6A09A7, 0x3F64AA59, 0x3F5EBE05, 0x3F584853, 0x3F514D3D, 0x3F49D112,
        0x3F41D870, 0x3F396842, 0x3F7FEC43, 0x3F7F4E6D, 0x3F7E1324, 0x3F7C3B28, 0x3F79C79D,
        0x3F76BA07, 0x3F731447, 0x3F6ED89E, 0x3F6A09A7, 0x3F64AA59, 0x3F5EBE05, 0x3F584853,
        0x3F514D3D, 0x3F49D112, 0x3F41D870, 0x3F396842, 0x3F7FEC43, 0x3F7F4E6D, 0x3F7E1324,
        0x3F7C3B28, 0x3F79C79D, 0x3F76BA07, 0x3F731447, 0x3F6ED89E, 0x3F6A09A7, 0x3F64AA59,
        0x3F5EBE05, 0x3F584853, 0x3F514D3D, 0x3F49D112, 0x3F41D870, 0x3F396842, 0x3F7FEC43,
        0x3F7F4E6D, 0x3F7E1324, 0x3F7C3B28, 0x3F79C79D, 0x3F76BA07, 0x3F731447, 0x3F6ED89E,
        0x3F6A09A7, 0x3F64AA59, 0x3F5EBE05, 0x3F584853, 0x3F514D3D, 0x3F49D112, 0x3F41D870,
        0x3F396842,
    ],
    [
        0x3F7FFB11, 0x3F7FD397, 0x3F7F84AB, 0x3F7F0E58, 0x3F7E70B0, 0x3F7DABCC, 0x3F7CBFC9,
        0x3F7BACCD, 0x3F7A7302, 0x3F791298, 0x3F778BC5, 0x3F75DEC6, 0x3F740BDD, 0x3F721352,
        0x3F6FF573, 0x3F6DB293, 0x3F6B4B0C, 0x3F68BF3C, 0x3F660F88, 0x3F633C5A, 0x3F604621,
        0x3F5D2D53, 0x3F59F26A, 0x3F5695E5, 0x3F531849, 0x3F4F7A1F, 0x3F4BBBF8, 0x3F47DE65,
        0x3F43E200, 0x3F3FC767, 0x3F3B8F3B, 0x3F373A23, 0x3F7FFB11, 0x3F7FD397, 0x3F7F84AB,
        0x3F7F0E58, 0x3F7E70B0, 0x3F7DABCC, 0x3F7CBFC9, 0x3F7BACCD, 0x3F7A7302, 0x3F791298,
        0x3F778BC5, 0x3F75DEC6, 0x3F740BDD, 0x3F721352, 0x3F6FF573, 0x3F6DB293, 0x3F6B4B0C,
        0x3F68BF3C, 0x3F660F88, 0x3F633C5A, 0x3F604621, 0x3F5D2D53, 0x3F59F26A, 0x3F5695E5,
        0x3F531849, 0x3F4F7A1F, 0x3F4BBBF8, 0x3F47DE65, 0x3F43E200, 0x3F3FC767, 0x3F3B8F3B,
        0x3F373A23,
    ],
    [
        0x3F7FFEC4, 0x3F7FF4E6, 0x3F7FE129, 0x3F7FC38F, 0x3F7F9C18, 0x3F7F6AC7, 0x3F7F2F9D,
        0x3F7EEA9D, 0x3F7E9BC9, 0x3F7E4323, 0x3F7DE0B1, 0x3F7D7474, 0x3F7CFE73, 0x3F7C7EB0,
        0x3F7BF531, 0x3F7B61FC, 0x3F7AC516, 0x3F7A1E84, 0x3F796E4E, 0x3F78B47B, 0x3F77F110,
        0x3F772417, 0x3F764D97, 0x3F756D97, 0x3F748422, 0x3F73913F, 0x3F7294F8, 0x3F718F57,
        0x3F708066, 0x3F6F6830, 0x3F6E46BE, 0x3F6D1C1D, 0x3F6BE858, 0x3F6AAB7B, 0x3F696591,
        0x3F6816A8, 0x3F66BECC, 0x3F655E0B, 0x3F63F473, 0x3F628210, 0x3F6106F2, 0x3F5F8327,
        0x3F5DF6BE, 0x3F5C61C7, 0x3F5AC450, 0x3F591E6A, 0x3F577026, 0x3F55B993, 0x3F53FAC3,
        0x3F5233C6, 0x3F5064AF, 0x3F4E8D90, 0x3F4CAE79, 0x3F4AC77F, 0x3F48D8B3, 0x3F46E22A,
        0x3F44E3F5, 0x3F42DE29, 0x3F40D0DA, 0x3F3EBC1B, 0x3F3CA003, 0x3F3A7CA4, 0x3F385216,
        0x3F36206C,
    ],
]);

/// Cos tables for DCT-IV (7 x 64 arrays)
static COS_TABLES: [[f32; 64]; 7] = table_from_bits([
    [
        0xBD0A8BD4, 0x3D0A8BD4, 0x3D0A8BD4, 0xBD0A8BD4, 0x3D0A8BD4, 0xBD0A8BD4, 0xBD0A8BD4,
        0x3D0A8BD4, 0x3D0A8BD4, 0xBD0A8BD4, 0xBD0A8BD4, 0x3D0A8BD4, 0xBD0A8BD4, 0x3D0A8BD4,
        0x3D0A8BD4, 0xBD0A8BD4, 0x3D0A8BD4, 0xBD0A8BD4, 0xBD0A8BD4, 0x3D0A8BD4, 0xBD0A8BD4,
        0x3D0A8BD4, 0x3D0A8BD4, 0xBD0A8BD4, 0xBD0A8BD4, 0x3D0A8BD4, 0x3D0A8BD4, 0xBD0A8BD4,
        0x3D0A8BD4, 0xBD0A8BD4, 0xBD0A8BD4, 0x3D0A8BD4, 0x3D0A8BD4, 0xBD0A8BD4, 0xBD0A8BD4,
        0x3D0A8BD4, 0xBD0A8BD4, 0x3D0A8BD4, 0x3D0A8BD4, 0xBD0A8BD4, 0xBD0A8BD4, 0x3D0A8BD4,
        0x3D0A8BD4, 0xBD0A8BD4, 0x3D0A8BD4, 0xBD0A8BD4, 0xBD0A8BD4, 0x3D0A8BD4, 0xBD0A8BD4,
        0x3D0A8BD4, 0x3D0A8BD4, 0xBD0A8BD4, 0x3D0A8BD4, 0xBD0A8BD4, 0xBD0A8BD4, 0x3D0A8BD4,
        0x3D0A8BD4, 0xBD0A8BD4, 0xBD0A8BD4, 0x3D0A8BD4, 0xBD0A8BD4, 0x3D0A8BD4, 0x3D0A8BD4,
        0xBD0A8BD4,
    ],
    [
        0xBE47C5C2, 0xBF0E39DA, 0x3E47C5C2, 0x3F0E39DA, 0x3E47C5C2, 0x3F0E39DA, 0xBE47C5C2,
        0xBF0E39DA, 0x3E47C5C2, 0x3F0E39DA, 0xBE47C5C2, 0xBF0E39DA, 0xBE47C5C2, 0xBF0E39DA,
        0x3E47C5C2, 0x3F0E39DA, 0x3E47C5C2, 0x3F0E39DA, 0xBE47C5C2, 0xBF0E39DA, 0xBE47C5C2,
        0xBF0E39DA, 0x3E47C5C2, 0x3F0E39DA, 0xBE47C5C2, 0xBF0E39DA, 0x3E47C5C2, 0x3F0E39DA,
        0x3E47C5C2, 0x3F0E39DA, 0xBE47C5C2, 0xBF0E39DA, 0x3E47C5C2, 0x3F0E39DA, 0xBE47C5C2,
        0xBF0E39DA, 0xBE47C5C2, 0xBF0E39DA, 0x3E47C5C2, 0x3F0E39DA, 0xBE47C5C2, 0xBF0E39DA,
        0x3E47C5C2, 0x3F0E39DA, 0x3E47C5C2, 0x3F0E39DA, 0xBE47C5C2, 0xBF0E39DA, 0xBE47C5C2,
        0xBF0E39DA, 0x3E47C5C2, 0x3F0E39DA, 0x3E47C5C2, 0x3F0E39DA, 0xBE47C5C2, 0xBF0E39DA,
        0x3E47C5C2, 0x3F0E39DA, 0xBE47C5C2, 0xBF0E39DA, 0xBE47C5C2, 0xBF0E39DA, 0x3E47C5C2,
        0x3F0E39DA,
    ],
    [
        0xBDC8BD36, 0xBE94A031, 0xBEF15AEA, 0xBF226799, 0x3DC8BD36, 0x3E94A031, 0x3EF15AEA,
        0x3F226799, 0x3DC8BD36, 0x3E94A031, 0x3EF15AEA, 0x3F226799, 0xBDC8BD36, 0xBE94A031,
        0xBEF15AEA, 0xBF226799, 0x3DC8BD36, 0x3E94A031, 0x3EF15AEA, 0x3F226799, 0xBDC8BD36,
        0xBE94A031, 0xBEF15AEA, 0xBF226799, 0xBDC8BD36, 0xBE94A031, 0xBEF15AEA, 0xBF226799,
        0x3DC8BD36, 0x3E94A031, 0x3EF15AEA, 0x3F226799, 0x3DC8BD36, 0x3E94A031, 0x3EF15AEA,
        0x3F226799, 0xBDC8BD36, 0xBE94A031, 0xBEF15AEA, 0xBF226799, 0xBDC8BD36, 0xBE94A031,
        0xBEF15AEA, 0xBF226799, 0x3DC8BD36, 0x3E94A031, 0x3EF15AEA, 0x3F226799, 0xBDC8BD36,
        0xBE94A031, 0xBEF15AEA, 0xBF226799, 0x3DC8BD36, 0x3E94A031, 0x3EF15AEA, 0x3F226799,
        0x3DC8BD36, 0x3E94A031, 0x3EF15AEA, 0x3F226799, 0xBDC8BD36, 0xBE94A031, 0xBEF15AEA,
        0xBF226799,
    ],
    [
        0xBD48FB30, 0xBE164083, 0xBE78CFCC, 0xBEAC7CD4, 0xBEDAE880, 0xBF039C3D, 0xBF187FC0,
        0xBF2BEB4A, 0x3D48FB30, 0x3E164083, 0x3E78CFCC, 0x3EAC7CD4, 0x3EDAE880, 0x3F039C3D,
        0x3F187FC0, 0x3F2BEB4A, 0x3D48FB30, 0x3E164083, 0x3E78CFCC, 0x3EAC7CD4, 0x3EDAE880,
        0x3F039C3D, 0x3F187FC0, 0x3F2BEB4A, 0xBD48FB30, 0xBE164083, 0xBE78CFCC, 0xBEAC7CD4,
        0xBEDAE880, 0xBF039C3D, 0xBF187FC0, 0xBF2BEB4A, 0x3D48FB30, 0x3E164083, 0x3E78CFCC,
        0x3EAC7CD4, 0x3EDAE880, 0x3F039C3D, 0x3F187FC0, 0x3F2BEB4A, 0xBD48FB30, 0xBE164083,
        0xBE78CFCC, 0xBEAC7CD4, 0xBEDAE880, 0xBF039C3D, 0xBF187FC0, 0xBF2BEB4A, 0xBD48FB30,
        0xBE164083, 0xBE78CFCC, 0xBEAC7CD4, 0xBEDAE880, 0xBF039C3D, 0xBF187FC0, 0xBF2BEB4A,
        0x3D48FB30, 0x3E164083, 0x3E78CFCC, 0x3EAC7CD4, 0x3EDAE880, 0x3F039C3D, 0x3F187FC0,
        0x3F2BEB4A,
    ],
    [
        0xBCC90AB0, 0xBD96A905, 0xBDFAB273, 0xBE2F10A2, 0xBE605C13, 0xBE888E93, 0xBEA09AE5,
        0xBEB8442A, 0xBECF7BCA, 0xBEE63375, 0xBEFC5D27, 0xBF08F59B, 0xBF13682A, 0xBF1D7FD1,
        0xBF273656, 0xBF3085BB, 0x3CC90AB0, 0x3D96A905, 0x3DFAB273, 0x3E2F10A2, 0x3E605C13,
        0x3E888E93, 0x3EA09AE5, 0x3EB8442A, 0x3ECF7BCA, 0x3EE63375, 0x3EFC5D27, 0x3F08F59B,
        0x3F13682A, 0x3F1D7FD1, 0x3F273656, 0x3F3085BB, 0x3CC90AB0, 0x3D96A905, 0x3DFAB273,
        0x3E2F10A2, 0x3E605C13, 0x3E888E93, 0x3EA09AE5, 0x3EB8442A, 0x3ECF7BCA, 0x3EE63375,
        0x3EFC5D27, 0x3F08F59B, 0x3F13682A, 0x3F1D7FD1, 0x3F273656, 0x3F3085BB, 0xBCC90AB0,
        0xBD96A905, 0xBDFAB273, 0xBE2F10A2, 0xBE605C13, 0xBE888E93, 0xBEA09AE5, 0xBEB8442A,
        0xBECF7BCA, 0xBEE63375, 0xBEFC5D27, 0xBF08F59B, 0xBF13682A, 0xBF1D7FD1, 0xBF273656,
        0xBF3085BB,
    ],
    [
        0xBC490E90, 0xBD16C32C, 0xBD7B2B74, 0xBDAFB680, 0xBDE1BC2E, 0xBE09CF86, 0xBE22ABB6,
        0xBE3B6ECF, 0xBE541501, 0xBE6C9A7F, 0xBE827DC0, 0xBE8E9A22, 0xBE9AA086, 0xBEA68F12,
        0xBEB263EF, 0xBEBE1D4A, 0xBEC9B953, 0xBED53641, 0xBEE0924F, 0xBEEBCBBB, 0xBEF6E0CB,
        0xBF00E7E4, 0xBF064B82, 0xBF0B9A6B, 0xBF10D3CD, 0xBF15F6D9, 0xBF1B02C6, 0xBF1FF6CB,
        0xBF24D225, 0xBF299415, 0xBF2E3BDE, 0xBF32C8C9, 0x3C490E90, 0x3D16C32C, 0x3D7B2B74,
        0x3DAFB680, 0x3DE1BC2E, 0x3E09CF86, 0x3E22ABB6, 0x3E3B6ECF, 0x3E541501, 0x3E6C9A7F,
        0x3E827DC0, 0x3E8E9A22, 0x3E9AA086, 0x3EA68F12, 0x3EB263EF, 0x3EBE1D4A, 0x3EC9B953,
        0x3ED53641, 0x3EE0924F, 0x3EEBCBBB, 0x3EF6E0CB, 0x3F00E7E4, 0x3F064B82, 0x3F0B9A6B,
        0x3F10D3CD, 0x3F15F6D9, 0x3F1B02C6, 0x3F1FF6CB, 0x3F24D225, 0x3F299415, 0x3F2E3BDE,
        0x3F32C8C9,
    ],
    [
        0xBBC90F88, 0xBC96C9B6, 0xBCFB49BA, 0xBD2FE007, 0xBD621469, 0xBD8A200A, 0xBDA3308C,
        0xBDBC3AC3, 0xBDD53DB9, 0xBDEE3876, 0xBE039502, 0xBE1008B7, 0xBE1C76DE, 0xBE28DEFC,
        0xBE354098, 0xBE419B37, 0xBE4DEE60, 0xBE5A3997, 0xBE667C66, 0xBE72B651, 0xBE7EE6E1,
        0xBE8586CE, 0xBE8B9507, 0xBE919DDD, 0xBE97A117, 0xBE9D9E78, 0xBEA395C5, 0xBEA986C4,
        0xBEAF713A, 0xBEB554EC, 0xBEBB31A0, 0xBEC1071E, 0xBEC6D529, 0xBECC9B8B, 0xBED25A09,
        0xBED8106B, 0xBEDDBE79, 0xBEE363FA, 0xBEE900B7, 0xBEEE9479, 0xBEF41F07, 0xBEF9A02D,
        0xBEFF17B2, 0xBF0242B1, 0xBF04F484, 0xBF07A136, 0xBF0A48AD, 0xBF0CEAD0, 0xBF0F8784,
        0xBF121EB0, 0xBF14B039, 0xBF173C07, 0xBF19C200, 0xBF1C420C, 0xBF1EBC12, 0xBF212FF9,
        0xBF239DA9, 0xBF26050A, 0xBF286605, 0xBF2AC082, 0xBF2D1469, 0xBF2F61A5, 0xBF31A81D,
        0xBF33E7BC,
    ],
]);

/// Apply IMDCT transform to dequantized spectra
pub fn imdct_transform(ch: &mut StChannel, subframe: usize) {
    // The IMDCT operates on fixed 128-sample buffers. The stage schedule below
    // only indexes within those arrays.
    let spectra = ch.spectra[subframe].as_mut_ptr();
    let temp = ch.temp.as_mut_ptr();

    butterfly_stage::<1, 64, false>(spectra, temp);
    butterfly_stage::<2, 32, true>(spectra, temp);
    butterfly_stage::<4, 16, false>(spectra, temp);
    butterfly_stage::<8, 8, true>(spectra, temp);
    butterfly_stage::<16, 4, false>(spectra, temp);
    butterfly_stage::<32, 2, true>(spectra, temp);
    butterfly_stage::<64, 1, false>(spectra, temp);

    dct_stage::<0, 64, 1, true>(spectra, temp);
    dct_stage::<1, 32, 2, false>(spectra, temp);
    dct_stage::<2, 16, 4, true>(spectra, temp);
    dct_stage::<3, 8, 8, false>(spectra, temp);
    dct_stage::<4, 4, 16, true>(spectra, temp);
    dct_stage::<5, 2, 32, false>(spectra, temp);
    dct_stage::<6, 1, 64, true>(spectra, temp);

    // Update output/IMDCT with overlapped window
    let wave = ch.wave[subframe].as_mut_ptr();
    let previous = ch.imdct_previous.as_mut_ptr();
    let window = IMDCT_WINDOW.as_ptr();
    for i in 0..HALF {
        unsafe {
            *wave.add(i) = *window.add(i) * *spectra.add(i + HALF) + *previous.add(i);
            *wave.add(i + HALF) = *window.add(i + HALF)
                * *spectra.add(HCA_SAMPLES_PER_SUBFRAME - 1 - i)
                - *previous.add(i + HALF);
            *previous.add(i) =
                *window.add(HCA_SAMPLES_PER_SUBFRAME - 1 - i) * *spectra.add(HALF - i - 1);
            *previous.add(i + HALF) = *window.add(HALF - i - 1) * *spectra.add(i);
        }
    }
}

#[inline(always)]
fn butterfly_stage<const COUNT1: usize, const COUNT2: usize, const TEMP_SRC: bool>(
    spectra: *mut f32,
    temp: *mut f32,
) {
    let mut d1_idx = 0usize;
    let mut d2_idx = COUNT2;
    let mut t1_idx = 0usize;

    if TEMP_SRC {
        for _ in 0..COUNT1 {
            for _ in 0..COUNT2 {
                unsafe {
                    let a = *temp.add(t1_idx);
                    let b = *temp.add(t1_idx + 1);
                    t1_idx += 2;

                    *spectra.add(d1_idx) = a + b;
                    *spectra.add(d2_idx) = a - b;
                }
                d1_idx += 1;
                d2_idx += 1;
            }
            d1_idx += COUNT2;
            d2_idx += COUNT2;
        }
    } else {
        for _ in 0..COUNT1 {
            for _ in 0..COUNT2 {
                unsafe {
                    let a = *spectra.add(t1_idx);
                    let b = *spectra.add(t1_idx + 1);
                    t1_idx += 2;

                    *temp.add(d1_idx) = a + b;
                    *temp.add(d2_idx) = a - b;
                }
                d1_idx += 1;
                d2_idx += 1;
            }
            d1_idx += COUNT2;
            d2_idx += COUNT2;
        }
    }
}

#[inline(always)]
fn dct_stage<const TABLE: usize, const COUNT1: usize, const COUNT2: usize, const TEMP_SRC: bool>(
    spectra: *mut f32,
    temp: *mut f32,
) {
    let sin_table = &SIN_TABLES[TABLE];
    let cos_table = &COS_TABLES[TABLE];
    let mut sin_idx = 0;
    let mut cos_idx = 0;

    let mut d1_idx = 0usize;
    let mut d2_idx = COUNT2 * 2 - 1;
    let mut s1_idx = 0usize;
    let mut s2_idx = COUNT2;

    if TEMP_SRC {
        for _ in 0..COUNT1 {
            for _ in 0..COUNT2 {
                unsafe {
                    let a = *temp.add(s1_idx);
                    let b = *temp.add(s2_idx);
                    s1_idx += 1;
                    s2_idx += 1;

                    let sin = sin_table[sin_idx];
                    let cos = cos_table[cos_idx];
                    sin_idx += 1;
                    cos_idx += 1;

                    *spectra.add(d1_idx) = a * sin - b * cos;
                    *spectra.add(d2_idx) = a * cos + b * sin;
                }
                d1_idx += 1;
                d2_idx -= 1;
            }
            s1_idx += COUNT2;
            s2_idx += COUNT2;
            d1_idx += COUNT2;
            d2_idx += COUNT2 * 3;
        }
    } else {
        for _ in 0..COUNT1 {
            for _ in 0..COUNT2 {
                unsafe {
                    let a = *spectra.add(s1_idx);
                    let b = *spectra.add(s2_idx);
                    s1_idx += 1;
                    s2_idx += 1;

                    let sin = sin_table[sin_idx];
                    let cos = cos_table[cos_idx];
                    sin_idx += 1;
                    cos_idx += 1;

                    *temp.add(d1_idx) = a * sin - b * cos;
                    *temp.add(d2_idx) = a * cos + b * sin;
                }
                d1_idx += 1;
                d2_idx -= 1;
            }
            s1_idx += COUNT2;
            s2_idx += COUNT2;
            d1_idx += COUNT2;
            d2_idx += COUNT2 * 3;
        }
    }
}