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#ifdef HAVE_CONFIG_H

#include "config.h"

#endif

#include <arm_neon.h>

#include "SigProc_FIX.h"

#include "define.h"

#define QA 24

#define A_LIMIT SILK_FIX_CONST( 0.99975, QA )

#define MUL32_FRAC_Q(a32, b32, Q) ((opus_int32)(silk_RSHIFT_ROUND64(silk_SMULL(a32, b32), Q)))

/* The difficulty is how to judge a 64-bit signed integer tmp64 is 32-bit overflowed,

* since NEON has no 64-bit min, max or comparison instructions.

* A failed idea is to compare the results of vmovn(tmp64) and vqmovn(tmp64) whether they are equal or not.

* However, this idea fails when the tmp64 is something like 0xFFFFFFF980000000.

* Here we know that mult2Q >= 1, so the highest bit (bit 63, sign bit) of tmp64 must equal to bit 62.

* tmp64 was shifted left by 1 and we got tmp64'. If high_half(tmp64') != 0 and high_half(tmp64') != -1,

* then we know that bit 31 to bit 63 of tmp64 can not all be the sign bit, and therefore tmp64 is 32-bit overflowed.

* That is, we judge if tmp64' > 0x00000000FFFFFFFF, or tmp64' <= 0xFFFFFFFF00000000.

* We use narrowing shift right 31 bits to tmp32' to save data bandwidth and instructions.

* That is, we judge if tmp32' > 0x00000000, or tmp32' <= 0xFFFFFFFF.

*/

/* Compute inverse of LPC prediction gain, and */

/* test if LPC coefficients are stable (all poles within unit circle) */

static OPUS_INLINE opus_int32 LPC_inverse_pred_gain_QA_neon( /* O Returns inverse prediction gain in energy domain, Q30 */

opus_int32 A_QA[ SILK_MAX_ORDER_LPC ], /* I Prediction coefficients */

const opus_int order /* I Prediction order */

)

{

opus_int k, n, mult2Q;

opus_int32 invGain_Q30, rc_Q31, rc_mult1_Q30, rc_mult2, tmp1, tmp2;

opus_int32 max, min;

int32x4_t max_s32x4, min_s32x4;

int32x2_t max_s32x2, min_s32x2;

max_s32x4 = vdupq_n_s32( silk_int32_MIN );

min_s32x4 = vdupq_n_s32( silk_int32_MAX );

invGain_Q30 = SILK_FIX_CONST( 1, 30 );

for( k = order - 1; k > 0; k-- ) {

int32x2_t rc_Q31_s32x2, rc_mult2_s32x2;

int64x2_t mult2Q_s64x2;

/* Check for stability */

if( ( A_QA[ k ] > A_LIMIT ) || ( A_QA[ k ] < -A_LIMIT ) ) {

return 0;

}

/* Set RC equal to negated AR coef */

rc_Q31 = -silk_LSHIFT( A_QA[ k ], 31 - QA );

/* rc_mult1_Q30 range: [ 1 : 2^30 ] */

rc_mult1_Q30 = silk_SUB32( SILK_FIX_CONST( 1, 30 ), silk_SMMUL( rc_Q31, rc_Q31 ) );

silk_assert( rc_mult1_Q30 > ( 1 << 15 ) ); /* reduce A_LIMIT if fails */

silk_assert( rc_mult1_Q30 <= ( 1 << 30 ) );

/* Update inverse gain */

/* invGain_Q30 range: [ 0 : 2^30 ] */

invGain_Q30 = silk_LSHIFT( silk_SMMUL( invGain_Q30, rc_mult1_Q30 ), 2 );

silk_assert( invGain_Q30 >= 0 );

silk_assert( invGain_Q30 <= ( 1 << 30 ) );

if( invGain_Q30 < SILK_FIX_CONST( 1.0f / MAX_PREDICTION_POWER_GAIN, 30 ) ) {

return 0;

}

/* rc_mult2 range: [ 2^30 : silk_int32_MAX ] */

mult2Q = 32 - silk_CLZ32( silk_abs( rc_mult1_Q30 ) );

rc_mult2 = silk_INVERSE32_varQ( rc_mult1_Q30, mult2Q + 30 );

/* Update AR coefficient */

rc_Q31_s32x2 = vdup_n_s32( rc_Q31 );

mult2Q_s64x2 = vdupq_n_s64( -mult2Q );

rc_mult2_s32x2 = vdup_n_s32( rc_mult2 );

for( n = 0; n < ( ( k + 1 ) >> 1 ) - 3; n += 4 ) {

/* We always calculate extra elements of A_QA buffer when ( k % 4 ) != 0, to take the advantage of SIMD parallelization. */

int32x4_t tmp1_s32x4, tmp2_s32x4, t0_s32x4, t1_s32x4, s0_s32x4, s1_s32x4, t_QA0_s32x4, t_QA1_s32x4;

int64x2_t t0_s64x2, t1_s64x2, t2_s64x2, t3_s64x2;

tmp1_s32x4 = vld1q_s32( A_QA + n );

tmp2_s32x4 = vld1q_s32( A_QA + k - n - 4 );

tmp2_s32x4 = vrev64q_s32( tmp2_s32x4 );

tmp2_s32x4 = vcombine_s32( vget_high_s32( tmp2_s32x4 ), vget_low_s32( tmp2_s32x4 ) );

t0_s32x4 = vqrdmulhq_lane_s32( tmp2_s32x4, rc_Q31_s32x2, 0 );

t1_s32x4 = vqrdmulhq_lane_s32( tmp1_s32x4, rc_Q31_s32x2, 0 );

t_QA0_s32x4 = vqsubq_s32( tmp1_s32x4, t0_s32x4 );

t_QA1_s32x4 = vqsubq_s32( tmp2_s32x4, t1_s32x4 );

t0_s64x2 = vmull_s32( vget_low_s32 ( t_QA0_s32x4 ), rc_mult2_s32x2 );

t1_s64x2 = vmull_s32( vget_high_s32( t_QA0_s32x4 ), rc_mult2_s32x2 );

t2_s64x2 = vmull_s32( vget_low_s32 ( t_QA1_s32x4 ), rc_mult2_s32x2 );

t3_s64x2 = vmull_s32( vget_high_s32( t_QA1_s32x4 ), rc_mult2_s32x2 );

t0_s64x2 = vrshlq_s64( t0_s64x2, mult2Q_s64x2 );

t1_s64x2 = vrshlq_s64( t1_s64x2, mult2Q_s64x2 );

t2_s64x2 = vrshlq_s64( t2_s64x2, mult2Q_s64x2 );

t3_s64x2 = vrshlq_s64( t3_s64x2, mult2Q_s64x2 );

t0_s32x4 = vcombine_s32( vmovn_s64( t0_s64x2 ), vmovn_s64( t1_s64x2 ) );

t1_s32x4 = vcombine_s32( vmovn_s64( t2_s64x2 ), vmovn_s64( t3_s64x2 ) );

s0_s32x4 = vcombine_s32( vshrn_n_s64( t0_s64x2, 31 ), vshrn_n_s64( t1_s64x2, 31 ) );

s1_s32x4 = vcombine_s32( vshrn_n_s64( t2_s64x2, 31 ), vshrn_n_s64( t3_s64x2, 31 ) );

max_s32x4 = vmaxq_s32( max_s32x4, s0_s32x4 );

min_s32x4 = vminq_s32( min_s32x4, s0_s32x4 );

max_s32x4 = vmaxq_s32( max_s32x4, s1_s32x4 );

min_s32x4 = vminq_s32( min_s32x4, s1_s32x4 );

t1_s32x4 = vrev64q_s32( t1_s32x4 );

t1_s32x4 = vcombine_s32( vget_high_s32( t1_s32x4 ), vget_low_s32( t1_s32x4 ) );

vst1q_s32( A_QA + n, t0_s32x4 );

vst1q_s32( A_QA + k - n - 4, t1_s32x4 );

}

for( ; n < (k + 1) >> 1; n++ ) {

opus_int64 tmp64;

tmp1 = A_QA[ n ];

tmp2 = A_QA[ k - n - 1 ];

tmp64 = silk_RSHIFT_ROUND64( silk_SMULL( silk_SUB_SAT32(tmp1,

MUL32_FRAC_Q( tmp2, rc_Q31, 31 ) ), rc_mult2 ), mult2Q);

if( tmp64 > silk_int32_MAX || tmp64 < silk_int32_MIN ) {

return 0;

}

A_QA[ n ] = ( opus_int32 )tmp64;

tmp64 = silk_RSHIFT_ROUND64( silk_SMULL( silk_SUB_SAT32(tmp2,

MUL32_FRAC_Q( tmp1, rc_Q31, 31 ) ), rc_mult2), mult2Q);

if( tmp64 > silk_int32_MAX || tmp64 < silk_int32_MIN ) {

return 0;

}

A_QA[ k - n - 1 ] = ( opus_int32 )tmp64;

}

}

/* Check for stability */

if( ( A_QA[ k ] > A_LIMIT ) || ( A_QA[ k ] < -A_LIMIT ) ) {

return 0;

}

max_s32x2 = vmax_s32( vget_low_s32( max_s32x4 ), vget_high_s32( max_s32x4 ) );

min_s32x2 = vmin_s32( vget_low_s32( min_s32x4 ), vget_high_s32( min_s32x4 ) );

max_s32x2 = vmax_s32( max_s32x2, vreinterpret_s32_s64( vshr_n_s64( vreinterpret_s64_s32( max_s32x2 ), 32 ) ) );

min_s32x2 = vmin_s32( min_s32x2, vreinterpret_s32_s64( vshr_n_s64( vreinterpret_s64_s32( min_s32x2 ), 32 ) ) );

max = vget_lane_s32( max_s32x2, 0 );

min = vget_lane_s32( min_s32x2, 0 );

if( ( max > 0 ) || ( min < -1 ) ) {

return 0;

}

/* Set RC equal to negated AR coef */

rc_Q31 = -silk_LSHIFT( A_QA[ 0 ], 31 - QA );

/* Range: [ 1 : 2^30 ] */

rc_mult1_Q30 = silk_SUB32( SILK_FIX_CONST( 1, 30 ), silk_SMMUL( rc_Q31, rc_Q31 ) );

/* Update inverse gain */

/* Range: [ 0 : 2^30 ] */

invGain_Q30 = silk_LSHIFT( silk_SMMUL( invGain_Q30, rc_mult1_Q30 ), 2 );

silk_assert( invGain_Q30 >= 0 );

silk_assert( invGain_Q30 <= ( 1 << 30 ) );

if( invGain_Q30 < SILK_FIX_CONST( 1.0f / MAX_PREDICTION_POWER_GAIN, 30 ) ) {

return 0;

}

return invGain_Q30;

}

/* For input in Q12 domain */

opus_int32 silk_LPC_inverse_pred_gain_neon( /* O Returns inverse prediction gain in energy domain, Q30 */

const opus_int16 *A_Q12, /* I Prediction coefficients, Q12 [order] */

const opus_int order /* I Prediction order */

)

{

#ifdef OPUS_CHECK_ASM

const opus_int32 invGain_Q30_c = silk_LPC_inverse_pred_gain_c( A_Q12, order );

#endif

opus_int32 invGain_Q30;

if( ( SILK_MAX_ORDER_LPC != 24 ) || ( order & 1 )) {

invGain_Q30 = silk_LPC_inverse_pred_gain_c( A_Q12, order );

}

else {

opus_int32 Atmp_QA[ SILK_MAX_ORDER_LPC ];

opus_int32 DC_resp;

int16x8_t t0_s16x8, t1_s16x8, t2_s16x8;

int32x4_t t0_s32x4;

const opus_int leftover = order & 7;

/* Increase Q domain of the AR coefficients */

t0_s16x8 = vld1q_s16( A_Q12 + 0 );

t1_s16x8 = vld1q_s16( A_Q12 + 8 );

if ( order > 16 ) {

t2_s16x8 = vld1q_s16( A_Q12 + 16 );

}

t0_s32x4 = vpaddlq_s16( t0_s16x8 );

switch( order - leftover )

{

case 24:

t0_s32x4 = vpadalq_s16( t0_s32x4, t2_s16x8 );

vst1q_s32( Atmp_QA + 16, vshll_n_s16( vget_low_s16 ( t2_s16x8 ), QA - 12 ) );

vst1q_s32( Atmp_QA + 20, vshll_n_s16( vget_high_s16( t2_s16x8 ), QA - 12 ) );

/* FALLTHROUGH */

case 16:

t0_s32x4 = vpadalq_s16( t0_s32x4, t1_s16x8 );

vst1q_s32( Atmp_QA + 8, vshll_n_s16( vget_low_s16 ( t1_s16x8 ), QA - 12 ) );

vst1q_s32( Atmp_QA + 12, vshll_n_s16( vget_high_s16( t1_s16x8 ), QA - 12 ) );

/* FALLTHROUGH */

case 8:

{

const int32x2_t t_s32x2 = vpadd_s32( vget_low_s32( t0_s32x4 ), vget_high_s32( t0_s32x4 ) );

const int64x1_t t_s64x1 = vpaddl_s32( t_s32x2 );

DC_resp = vget_lane_s32( vreinterpret_s32_s64( t_s64x1 ), 0 );

vst1q_s32( Atmp_QA + 0, vshll_n_s16( vget_low_s16 ( t0_s16x8 ), QA - 12 ) );

vst1q_s32( Atmp_QA + 4, vshll_n_s16( vget_high_s16( t0_s16x8 ), QA - 12 ) );

}

break;

default:

DC_resp = 0;

break;

}

A_Q12 += order - leftover;

switch( leftover )

{

case 6:

DC_resp += (opus_int32)A_Q12[ 5 ];

DC_resp += (opus_int32)A_Q12[ 4 ];

Atmp_QA[ order - leftover + 5 ] = silk_LSHIFT32( (opus_int32)A_Q12[ 5 ], QA - 12 );

Atmp_QA[ order - leftover + 4 ] = silk_LSHIFT32( (opus_int32)A_Q12[ 4 ], QA - 12 );

/* FALLTHROUGH */

case 4:

DC_resp += (opus_int32)A_Q12[ 3 ];

DC_resp += (opus_int32)A_Q12[ 2 ];

Atmp_QA[ order - leftover + 3 ] = silk_LSHIFT32( (opus_int32)A_Q12[ 3 ], QA - 12 );

Atmp_QA[ order - leftover + 2 ] = silk_LSHIFT32( (opus_int32)A_Q12[ 2 ], QA - 12 );

/* FALLTHROUGH */

case 2:

DC_resp += (opus_int32)A_Q12[ 1 ];

DC_resp += (opus_int32)A_Q12[ 0 ];

Atmp_QA[ order - leftover + 1 ] = silk_LSHIFT32( (opus_int32)A_Q12[ 1 ], QA - 12 );

Atmp_QA[ order - leftover + 0 ] = silk_LSHIFT32( (opus_int32)A_Q12[ 0 ], QA - 12 );

/* FALLTHROUGH */

default:

break;

}

/* If the DC is unstable, we don't even need to do the full calculations */

if( DC_resp >= 4096 ) {

invGain_Q30 = 0;

} else {

invGain_Q30 = LPC_inverse_pred_gain_QA_neon( Atmp_QA, order );

}

}

#ifdef OPUS_CHECK_ASM

silk_assert( invGain_Q30_c == invGain_Q30 );

#endif

return invGain_Q30;

}