From eefd26ffb05a77fd8c94f98526bd75ebddc76226 Mon Sep 17 00:00:00 2001
From: Kyle Siefring <kylesiefring@gmail.com>
Date: Mon, 20 Aug 2018 16:32:40 -0400
Subject: [PATCH] Implement idct 4x4 in rust. (#464)
* Implement idct 4x4 in rust.
* Add uncommited changes [squashme]
* Make some changes based on code review.
* More changes.
* For code review
---
src/transform.rs | 108 +++++++++++++++++++++++++++++++++++++++++++----
1 file changed, 100 insertions(+), 8 deletions(-)
diff --git a/src/transform.rs b/src/transform.rs
index 427304c9..e4eea8c3 100755
--- a/src/transform.rs
+++ b/src/transform.rs
@@ -9,9 +9,97 @@
extern crate libc;
+use std::cmp;
+
use partition::TxSize;
use partition::TxType;
+use util::*;
+
+static COSPI_INV: [i32; 64] = [
+ 4096, 4095, 4091, 4085, 4076, 4065, 4052, 4036, 4017, 3996, 3973, 3948,
+ 3920, 3889, 3857, 3822, 3784, 3745, 3703, 3659, 3612, 3564, 3513, 3461,
+ 3406, 3349, 3290, 3229, 3166, 3102, 3035, 2967, 2896, 2824, 2751, 2675,
+ 2598, 2520, 2440, 2359, 2276, 2191, 2106, 2019, 1931, 1842, 1751, 1660,
+ 1567, 1474, 1380, 1285, 1189, 1092, 995, 897, 799, 700, 601, 501, 401, 301,
+ 201, 101,
+];
+
+// performs half a butterfly
+#[inline]
+fn half_btf(w0: i32, in0: i32, w1: i32, in1: i32, bit: usize) -> i32 {
+ let result = (w0 * in0) + (w1 * in1);
+ round_shift(result, bit)
+}
+
+#[inline]
+fn round_shift(value: i32, bit: usize) -> i32 {
+ (value + (1 << (bit - 1))) >> bit
+}
+
+// clamps value to a signed integer type of bit bits
+#[inline]
+fn clamp_value(value: i32, bit: usize) -> i32 {
+ let max_value: i32 = ((1i64 << (bit - 1)) - 1) as i32;
+ let min_value: i32 = (-(1i64 << (bit - 1))) as i32;
+ clamp(value, min_value, max_value)
+}
+
+fn av1_idct4(input: [i32; 4], output: &mut [i32], range: usize) {
+ let cos_bit = 12;
+ // stage 0
+
+ // stage 1
+ let stg1 = [input[0], input[2], input[1], input[3]];
+
+ // stage 2
+ let stg2 = [
+ half_btf(COSPI_INV[32], stg1[0], COSPI_INV[32], stg1[1], cos_bit),
+ half_btf(COSPI_INV[32], stg1[0], -COSPI_INV[32], stg1[1], cos_bit),
+ half_btf(COSPI_INV[48], stg1[2], -COSPI_INV[16], stg1[3], cos_bit),
+ half_btf(COSPI_INV[16], stg1[2], COSPI_INV[48], stg1[3], cos_bit)
+ ];
+
+ // stage 3
+ output[0] = clamp_value(stg2[0] + stg2[3], range);
+ output[1] = clamp_value(stg2[1] + stg2[2], range);
+ output[2] = clamp_value(stg2[1] - stg2[2], range);
+ output[3] = clamp_value(stg2[0] - stg2[3], range);
+}
+
+fn inv_txfm2d_add_4x4_rs(
+ input: &[i32], output: &mut [u16], stride: usize, bd: usize
+) {
+ let mut buffer = [0i32; 4 * 4];
+ // perform inv txfm on every row
+ let range = bd + 8;
+ for (input_slice, buffer_slice) in input.chunks(4).zip(buffer.chunks_mut(4))
+ {
+ let mut temp_in: [i32; 4] = [0; 4];
+ for (raw, clamped) in input_slice.iter().zip(temp_in.iter_mut()) {
+ *clamped = clamp_value(*raw, range);
+ }
+ av1_idct4(temp_in, buffer_slice, range);
+ }
+
+ // perform inv txfm on every col
+ let range = cmp::max(bd + 6, 16);
+ for c in 0..4 {
+ let mut temp_in: [i32; 4] = [0; 4];
+ let mut temp_out: [i32; 4] = [0; 4];
+ for (raw, clamped) in buffer[c..].iter().step_by(4).zip(temp_in.iter_mut())
+ {
+ *clamped = clamp_value(*raw, range);
+ }
+ av1_idct4(temp_in, &mut temp_out, range);
+ for (temp, out) in
+ temp_out.iter().zip(output[c..].iter_mut().step_by(stride).take(4)) {
+ *out =
+ clamp(*out as i32 + round_shift(*temp, 4), 0, (1 << bd) - 1) as u16;
+ }
+ }
+}
+
// In libaom, functions that have more than one specialization use function
// pointers, so we need to declare them as static fields and call them
// indirectly. Otherwise, we call SSE or C variants directly. To fully
@@ -136,14 +224,18 @@ fn iht4x4_add(
) {
// SIMD code may assert for transform types beyond TxType::IDTX.
if tx_type < TxType::IDTX {
- unsafe {
- av1_inv_txfm2d_add_4x4(
- input.as_ptr(),
- output.as_mut_ptr(),
- stride as libc::c_int,
- tx_type as libc::c_int,
- bit_depth as libc::c_int
- );
+ if tx_type == TxType::DCT_DCT {
+ inv_txfm2d_add_4x4_rs(input, output, stride, bit_depth);
+ } else {
+ unsafe {
+ av1_inv_txfm2d_add_4x4(
+ input.as_ptr(),
+ output.as_mut_ptr(),
+ stride as libc::c_int,
+ tx_type as libc::c_int,
+ bit_depth as libc::c_int
+ );
+ }
}
} else {
unsafe {
--
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