// Copyright (c) 2017-2022, The rav1e contributors. All rights reserved

//

// This source code is subject to the terms of the BSD 2 Clause License and

// the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License

// was not distributed with this source code in the LICENSE file, you can

// obtain it at www.aomedia.org/license/software. If the Alliance for Open

// Media Patent License 1.0 was not distributed with this source code in the

// PATENTS file, you can obtain it at www.aomedia.org/license/patent.

#![allow(non_upper_case_globals)]

mod tables;

cfg_if::cfg_if! {

  if #[cfg(nasm_x86_64)] {

    pub use crate::asm::x86::quantize::*;

  } else {

    pub use self::rust::*;

  }

}

pub use tables::*;

use crate::scan_order::av1_scan_orders;

use crate::transform::{TxSize, TxType};

use crate::util::*;

use std::convert::Into;

use std::mem;

use std::num::{NonZeroU16, NonZeroU32, NonZeroU64};

pub fn get_log_tx_scale(tx_size: TxSize) -> usize {

  let num_pixels = tx_size.area();

  Into::<usize>::into(num_pixels > 256)

    + Into::<usize>::into(num_pixels > 1024)

}

pub fn dc_q(qindex: u8, delta_q: i8, bit_depth: usize) -> NonZeroU16 {

  let dc_q: [&[NonZeroU16; 256]; 3] =

    [&dc_qlookup_Q3, &dc_qlookup_10_Q3, &dc_qlookup_12_Q3];

  let bd = ((bit_depth ^ 8) >> 1).min(2);

  dc_q[bd][((qindex as isize + delta_q as isize).max(0) as usize).min(255)]

}

pub fn ac_q(qindex: u8, delta_q: i8, bit_depth: usize) -> NonZeroU16 {

  let ac_q: [&[NonZeroU16; 256]; 3] =

    [&ac_qlookup_Q3, &ac_qlookup_10_Q3, &ac_qlookup_12_Q3];

  let bd = ((bit_depth ^ 8) >> 1).min(2);

  ac_q[bd][((qindex as isize + delta_q as isize).max(0) as usize).min(255)]

}

// TODO: Handle lossless properly.

fn select_qi(quantizer: i64, qlookup: &[NonZeroU16; QINDEX_RANGE]) -> u8 {

  if quantizer < qlookup[MINQ].get() as i64 {

    MINQ as u8

  } else if quantizer >= qlookup[MAXQ].get() as i64 {

    MAXQ as u8

  } else {

    match qlookup

      .binary_search(&NonZeroU16::new(quantizer as u16).expect("Not zero"))

    {

      Ok(qi) => qi as u8,

      Err(qi) => {

        debug_assert!(qi > MINQ);

        debug_assert!(qi <= MAXQ);

        // Pick the closest quantizer in the log domain.

        let qthresh =

          (qlookup[qi - 1].get() as i32) * (qlookup[qi].get() as i32);

        let q2_i32 = (quantizer as i32) * (quantizer as i32);

        if q2_i32 < qthresh {

          (qi - 1) as u8

        } else {

          qi as u8

        }

      }

    }

  }

}

pub fn select_dc_qi(quantizer: i64, bit_depth: usize) -> u8 {

  let qlookup = match bit_depth {

    8 => &dc_qlookup_Q3,

    10 => &dc_qlookup_10_Q3,

    12 => &dc_qlookup_12_Q3,

    _ => unimplemented!(),

  };

  select_qi(quantizer, qlookup)

}

pub fn select_ac_qi(quantizer: i64, bit_depth: usize) -> u8 {

  let qlookup = match bit_depth {

    8 => &ac_qlookup_Q3,

    10 => &ac_qlookup_10_Q3,

    12 => &ac_qlookup_12_Q3,

    _ => unimplemented!(),

  };

  select_qi(quantizer, qlookup)

}

#[derive(Debug, Clone, Copy)]

pub struct QuantizationContext {

  log_tx_scale: usize,

  dc_quant: NonZeroU16,

  dc_offset: u32,

  dc_mul_add: (u32, u32, u32),

  ac_quant: NonZeroU16,

  ac_offset_eob: u32,

  ac_offset0: u32,

  ac_offset1: u32,

  ac_mul_add: (u32, u32, u32),

}

impl Default for QuantizationContext {

  fn default() -> Self {

    QuantizationContext {

      dc_quant: NonZeroU16::new(1).expect("Not zero"),

      ac_quant: NonZeroU16::new(1).expect("Not zero"),

      log_tx_scale: Default::default(),

      dc_offset: Default::default(),

      dc_mul_add: Default::default(),

      ac_offset_eob: Default::default(),

      ac_offset0: Default::default(),

      ac_offset1: Default::default(),

      ac_mul_add: Default::default(),

    }

  }

}

fn divu_gen(d: NonZeroU32) -> (u32, u32, u32) {

  let nbits = (mem::size_of_val(&d) as u64) * 8;

  let m = nbits - d.leading_zeros() as u64 - 1;

  if d.is_power_of_two() {

    (0xFFFF_FFFF, 0xFFFF_FFFF, m as u32)

  } else {

    let d = NonZeroU64::from(d);

    let t = (1u64 << (m + nbits)) / d;

    let d = d.get();

    let r = (t * d + d) & ((1 << nbits) - 1);

    if r <= 1u64 << m {

      (t as u32 + 1, 0u32, m as u32)

    } else {

      (t as u32, t as u32, m as u32)

    }

  }

}

#[inline]

const fn divu_pair(x: u32, d: (u32, u32, u32)) -> u32 {

  let x = x as u64;

  let (a, b, shift) = d;

  let shift = shift as u64;

  let a = a as u64;

  let b = b as u64;

  (((a * x + b) >> 32) >> shift) as u32

}

Unexecuted instantiation: rav1e::quantize::divu_pair

Unexecuted instantiation: rav1e::quantize::divu_pair

#[inline]

const fn copysign(value: u32, signed: i32) -> i32 {

  if signed < 0 {

    -(value as i32)

  } else {

    value as i32

  }

}

Unexecuted instantiation: rav1e::quantize::copysign

Unexecuted instantiation: rav1e::quantize::copysign

#[cfg(test)]

mod test {

  use super::*;

  use crate::transform::TxSize::*;

  #[test]

  fn test_divu_pair() {

    for d in 1..1024 {

      for x in 0..1000 {

        let ab = divu_gen(NonZeroU32::new(d).unwrap());

        assert_eq!(x / d, divu_pair(x, ab));

      }

    }

  }

  #[test]

  fn gen_divu_table() {

    let b: Vec<(u32, u32, u32)> =

      dc_qlookup_Q3.iter().map(|&v| divu_gen(v.into())).collect();

    println!("{:?}", b);

  }

  #[test]

  fn test_tx_log_scale() {

    let tx_sizes = [

      (TX_4X4, 0),

      (TX_8X8, 0),

      (TX_16X16, 0),

      (TX_32X32, 1),

      (TX_64X64, 2),

      (TX_4X8, 0),

      (TX_8X4, 0),

      (TX_8X16, 0),

      (TX_16X8, 0),

      (TX_16X32, 1),

      (TX_32X16, 1),

      (TX_32X64, 2),

      (TX_64X32, 2),

      (TX_4X16, 0),

      (TX_16X4, 0),

      (TX_8X32, 0),

      (TX_32X8, 0),

      (TX_16X64, 1),

      (TX_64X16, 1),

    ];

    for &tx_size in tx_sizes.iter() {

      assert!(tx_size.1 == get_log_tx_scale(tx_size.0));

    }

  }

}

impl QuantizationContext {

  pub fn update(

    &mut self, qindex: u8, tx_size: TxSize, is_intra: bool, bit_depth: usize,

    dc_delta_q: i8, ac_delta_q: i8,

  ) {

    self.log_tx_scale = get_log_tx_scale(tx_size);

    self.dc_quant = dc_q(qindex, dc_delta_q, bit_depth);

    self.dc_mul_add = divu_gen(self.dc_quant.into());

    self.ac_quant = ac_q(qindex, ac_delta_q, bit_depth);

    self.ac_mul_add = divu_gen(self.ac_quant.into());

    // All of these biases were derived by measuring the cost of coding

    // a zero vs coding a one on any given coefficient position, or, in

    // the case of the EOB bias, the cost of coding the block with

    // the chosen EOB (rounding to one) vs rounding to zero and continuing

    // to choose a new EOB. This was done over several clips, with the

    // average of the bit costs taken over all blocks in the set, and a new

    // bias derived via the method outlined in Jean-Marc Valin's

    // Journal of Dubious Theoretical Results[1], aka:

    //

    // lambda = ln(2) / 6.0

    // threshold = 0.5 + (lambda * avg_rate_diff) / 2.0

    // bias = 1 - threshold

    //

    // lambda is a constant since our offsets are already adjusted for the

    // quantizer.

    //

    // Biases were then updated, and cost collection was re-run, until

    // the calculated biases started to converge after 2-4 iterations.

    //

    // In theory, the rounding biases for inter should be somewhat smaller

    // than the biases for intra, but this turns out to only be the case

    // for EOB optimization, or at least, is covered by EOB optimization.

    // The RD-optimal rounding biases for the actual coefficients seem

    // to be quite close (+/- 1/256), for both inter and intra,

    // post-deadzoning.

    //

    // [1] https://jmvalin.ca/notes/theoretical_results.pdf

    self.dc_offset =

      self.dc_quant.get() as u32 * (if is_intra { 109 } else { 108 }) / 256;

    self.ac_offset0 =

      self.ac_quant.get() as u32 * (if is_intra { 98 } else { 97 }) / 256;

    self.ac_offset1 =

      self.ac_quant.get() as u32 * (if is_intra { 109 } else { 108 }) / 256;

    self.ac_offset_eob =

      self.ac_quant.get() as u32 * (if is_intra { 88 } else { 44 }) / 256;

  }

  #[inline]

  pub fn quantize<T: Coefficient>(

    &self, coeffs: &[T], qcoeffs: &mut [T], tx_size: TxSize, tx_type: TxType,

  ) -> u16 {

    let scan = av1_scan_orders[tx_size as usize][tx_type as usize].scan;

    let iscan = av1_scan_orders[tx_size as usize][tx_type as usize].iscan;

    qcoeffs[0] = {

      let coeff: i32 = i32::cast_from(coeffs[0]) << self.log_tx_scale;

      let abs_coeff = coeff.unsigned_abs();

      T::cast_from(copysign(

        divu_pair(abs_coeff + self.dc_offset, self.dc_mul_add),

        coeff,

      ))

    };

    // Find the last non-zero coefficient using our smaller biases and

    // zero everything else.

    // This threshold is such that `abs(coeff) < deadzone` implies:

    // (abs(coeff << log_tx_scale) + ac_offset_eob) / ac_quant == 0

    let deadzone = T::cast_from(

      (self.ac_quant.get() as usize - self.ac_offset_eob as usize)

        .align_power_of_two_and_shift(self.log_tx_scale),

    );

    let eob = {

      let eob_minus_one = iscan

        .iter()

        .zip(coeffs)

        .map(|(&i, &c)| if c.abs() >= deadzone { i } else { 0 })

Unexecuted instantiation: <rav1e::quantize::QuantizationContext>::quantize::<i32>::{closure#0}

Unexecuted instantiation: <rav1e::quantize::QuantizationContext>::quantize::<i16>::{closure#0}

        .max()

        .unwrap_or(0);

      // We skip the DC coefficient since it has its own quantizer index.

      if eob_minus_one > 0 {

        eob_minus_one + 1

      } else {

        u16::from(qcoeffs[0] != T::cast_from(0))

      }

    };

    // Here we use different rounding biases depending on whether we've

    // had recent coefficients that are larger than one, or less than

    // one. The reason for this is that a block usually has a chunk of

    // large coefficients and a tail of zeroes and ones, and the tradeoffs

    // for coding these two are different. In the tail of zeroes and ones,

    // you'll likely end up spending most bits just saying where that

    // coefficient is in the block, whereas in the chunk of larger

    // coefficients, most bits will be spent on coding its magnitude.

    // To that end, we want to bias more toward rounding to zero for

    // that tail of zeroes and ones than we do for the larger coefficients.

    let mut level_mode = 1;

    let ac_quant = self.ac_quant.get() as u32;

    for &pos in scan.iter().take(usize::from(eob)).skip(1) {

      let coeff = i32::cast_from(coeffs[pos as usize]) << self.log_tx_scale;

      let abs_coeff = coeff.unsigned_abs();

      let level0 = divu_pair(abs_coeff, self.ac_mul_add);

      let offset = if level0 > 1 - level_mode {

        self.ac_offset1

      } else {

        self.ac_offset0

      };

      let abs_qcoeff: u32 =

        level0 + (abs_coeff + offset >= (level0 + 1) * ac_quant) as u32;

      if level_mode != 0 && abs_qcoeff == 0 {

        level_mode = 0;

      } else if abs_qcoeff > 1 {

        level_mode = 1;

      }

      qcoeffs[pos as usize] = T::cast_from(copysign(abs_qcoeff, coeff));

    }

    // Rather than zeroing the tail in scan order, assume that qcoeffs is

    // pre-filled with zeros.

    // Check the eob is correct

    debug_assert_eq!(

      usize::from(eob),

      scan

        .iter()

        .rposition(|&i| qcoeffs[i as usize] != T::cast_from(0))

        .map(|n| n + 1)

        .unwrap_or(0)

    );

    eob

  }

Unexecuted instantiation: <rav1e::quantize::QuantizationContext>::quantize::<i32>

Unexecuted instantiation: <rav1e::quantize::QuantizationContext>::quantize::<i16>

}

pub mod rust {

  use super::*;

  use crate::cpu_features::CpuFeatureLevel;

  use std::mem::MaybeUninit;

  pub fn dequantize<T: Coefficient>(

    qindex: u8, coeffs: &[T], _eob: u16, rcoeffs: &mut [MaybeUninit<T>],

    tx_size: TxSize, bit_depth: usize, dc_delta_q: i8, ac_delta_q: i8,

    _cpu: CpuFeatureLevel,

  ) {

    let log_tx_scale = get_log_tx_scale(tx_size) as i32;

    let offset = (1 << log_tx_scale) - 1;

    let dc_quant = dc_q(qindex, dc_delta_q, bit_depth).get() as i32;

    let ac_quant = ac_q(qindex, ac_delta_q, bit_depth).get() as i32;

    for (i, (r, c)) in rcoeffs

      .iter_mut()

      .zip(coeffs.iter().map(|&c| i32::cast_from(c)))

Unexecuted instantiation: rav1e::quantize::rust::dequantize::<i32>::{closure#0}

Unexecuted instantiation: rav1e::quantize::rust::dequantize::<i16>::{closure#0}

      .enumerate()

    {

      let quant = if i == 0 { dc_quant } else { ac_quant };

      r.write(T::cast_from(

        (c * quant + ((c >> 31) & offset)) >> log_tx_scale,

      ));

    }

  }

Unexecuted instantiation: rav1e::quantize::rust::dequantize::<i32>

Unexecuted instantiation: rav1e::quantize::rust::dequantize::<i16>

}