rewrite Disto4x4 in enc_neon.c with intrinsic

Performance test:
Platform: A9
Input data: bryce.yuv  11158x2156
performance of assembly is the base. Less ratio is better.
|toolchain |assembly |intrinsic |
|gcc4.6    |100%     |97.15%    |
|gcc4.8    |100%     |95.51     |

Change-Id: Idc2446685acdeb58a4dbdcdae533c68a83a1b879
This commit is contained in:
Yang Zhang 2014-09-04 17:20:52 +08:00 committed by James Zern
parent d4471637ef
commit ab70794ddb

View File

@ -548,324 +548,166 @@ static void FTransformWHT(const int16_t* src, int16_t* out) {
// We try to match the spectral content (weighted) between source and
// reconstructed samples.
// This code works but is *slower* than the inlined-asm version below
// (with gcc-4.6). So we disable it for now. Later, it'll be conditional to
// USE_INTRINSICS define.
// With gcc-4.8, it's only slightly slower than the inlined.
#if defined(USE_INTRINSICS)
// a 0123, b 0123
// a 4567, b 4567
// a 89ab, b 89ab
// a cdef, b cdef
//
// transpose
//
// a 048c, b 048c
// a 159d, b 159d
// a 26ae, b 26ae
// a 37bf, b 37bf
//
static WEBP_INLINE uint8x8x4_t DistoTranspose4x4U8(uint8x8x4_t d4_in) {
const uint8x8x2_t d2_tmp0 = vtrn_u8(d4_in.val[0], d4_in.val[1]);
const uint8x8x2_t d2_tmp1 = vtrn_u8(d4_in.val[2], d4_in.val[3]);
const uint16x4x2_t d2_tmp2 = vtrn_u16(vreinterpret_u16_u8(d2_tmp0.val[0]),
vreinterpret_u16_u8(d2_tmp1.val[0]));
const uint16x4x2_t d2_tmp3 = vtrn_u16(vreinterpret_u16_u8(d2_tmp0.val[1]),
vreinterpret_u16_u8(d2_tmp1.val[1]));
// Zero extend an uint16x4_t 'v' to an int32x4_t.
static WEBP_INLINE int32x4_t ConvertU16ToS32(uint16x4_t v) {
return vreinterpretq_s32_u32(vmovl_u16(v));
d4_in.val[0] = vreinterpret_u8_u16(d2_tmp2.val[0]);
d4_in.val[2] = vreinterpret_u8_u16(d2_tmp2.val[1]);
d4_in.val[1] = vreinterpret_u8_u16(d2_tmp3.val[0]);
d4_in.val[3] = vreinterpret_u8_u16(d2_tmp3.val[1]);
return d4_in;
}
// Does a regular 4x4 transpose followed by an adjustment of the upper columns
// in the inner rows to restore the source order of differences,
// i.e., a0 - a1 | a3 - a2.
static WEBP_INLINE int32x4x4_t DistoTranspose4x4(const int32x4x4_t rows) {
int32x4x4_t out = Transpose4x4(rows);
// restore source order in the columns containing differences.
const int32x2_t r1h = vget_high_s32(out.val[1]);
const int32x2_t r2h = vget_high_s32(out.val[2]);
out.val[1] = vcombine_s32(vget_low_s32(out.val[1]), r2h);
out.val[2] = vcombine_s32(vget_low_s32(out.val[2]), r1h);
return out;
static WEBP_INLINE int16x8x4_t DistoTranspose4x4S16(int16x8x4_t q4_in) {
const int16x8x2_t q2_tmp0 = vtrnq_s16(q4_in.val[0], q4_in.val[1]);
const int16x8x2_t q2_tmp1 = vtrnq_s16(q4_in.val[2], q4_in.val[3]);
const int32x4x2_t q2_tmp2 = vtrnq_s32(vreinterpretq_s32_s16(q2_tmp0.val[0]),
vreinterpretq_s32_s16(q2_tmp1.val[0]));
const int32x4x2_t q2_tmp3 = vtrnq_s32(vreinterpretq_s32_s16(q2_tmp0.val[1]),
vreinterpretq_s32_s16(q2_tmp1.val[1]));
q4_in.val[0] = vreinterpretq_s16_s32(q2_tmp2.val[0]);
q4_in.val[2] = vreinterpretq_s16_s32(q2_tmp2.val[1]);
q4_in.val[1] = vreinterpretq_s16_s32(q2_tmp3.val[0]);
q4_in.val[3] = vreinterpretq_s16_s32(q2_tmp3.val[1]);
return q4_in;
}
static WEBP_INLINE int32x4x4_t DistoHorizontalPass(const uint8x8_t r0r1,
const uint8x8_t r2r3) {
// a0 = in[0] + in[2] | a1 = in[1] + in[3]
const uint16x8_t a0a1 = vaddl_u8(r0r1, r2r3);
// a3 = in[0] - in[2] | a2 = in[1] - in[3]
const uint16x8_t a3a2 = vsubl_u8(r0r1, r2r3);
const int32x4_t tmp0 = vpaddlq_s16(vreinterpretq_s16_u16(a0a1)); // a0 + a1
const int32x4_t tmp1 = vpaddlq_s16(vreinterpretq_s16_u16(a3a2)); // a3 + a2
// no pairwise subtraction; reorder to perform tmp[2]/tmp[3] calculations.
// a0a0 a3a3 a0a0 a3a3 a0a0 a3a3 a0a0 a3a3
// a1a1 a2a2 a1a1 a2a2 a1a1 a2a2 a1a1 a2a2
const int16x8x2_t transpose =
vtrnq_s16(vreinterpretq_s16_u16(a0a1), vreinterpretq_s16_u16(a3a2));
// tmp[3] = a0 - a1 | tmp[2] = a3 - a2
const int32x4_t tmp32_1 = vsubl_s16(vget_low_s16(transpose.val[0]),
vget_low_s16(transpose.val[1]));
const int32x4_t tmp32_2 = vsubl_s16(vget_high_s16(transpose.val[0]),
vget_high_s16(transpose.val[1]));
// [0]: tmp[3] [1]: tmp[2]
const int32x4x2_t split = vtrnq_s32(tmp32_1, tmp32_2);
const int32x4x4_t res = { { tmp0, tmp1, split.val[1], split.val[0] } };
return res;
static WEBP_INLINE int16x8x4_t DistoHorizontalPass(const uint8x8x4_t d4_in) {
// {a0, a1} = {in[0] + in[2], in[1] + in[3]}
// {a3, a2} = {in[0] - in[2], in[1] - in[3]}
const int16x8_t q_a0 = vreinterpretq_s16_u16(vaddl_u8(d4_in.val[0],
d4_in.val[2]));
const int16x8_t q_a1 = vreinterpretq_s16_u16(vaddl_u8(d4_in.val[1],
d4_in.val[3]));
const int16x8_t q_a3 = vreinterpretq_s16_u16(vsubl_u8(d4_in.val[0],
d4_in.val[2]));
const int16x8_t q_a2 = vreinterpretq_s16_u16(vsubl_u8(d4_in.val[1],
d4_in.val[3]));
int16x8x4_t q4_out;
// tmp[0] = a0 + a1
// tmp[1] = a3 + a2
// tmp[2] = a3 - a2
// tmp[3] = a0 - a1
INIT_VECTOR4(q4_out,
vaddq_s16(q_a0, q_a1), vaddq_s16(q_a3, q_a2),
vsubq_s16(q_a3, q_a2), vsubq_s16(q_a0, q_a1));
return q4_out;
}
static WEBP_INLINE int32x4x4_t DistoVerticalPass(const int32x4x4_t rows) {
// a0 = tmp[0 + i] + tmp[8 + i];
const int32x4_t a0 = vaddq_s32(rows.val[0], rows.val[1]);
// a1 = tmp[4 + i] + tmp[12+ i];
const int32x4_t a1 = vaddq_s32(rows.val[2], rows.val[3]);
// a2 = tmp[4 + i] - tmp[12+ i];
const int32x4_t a2 = vsubq_s32(rows.val[2], rows.val[3]);
// a3 = tmp[0 + i] - tmp[8 + i];
const int32x4_t a3 = vsubq_s32(rows.val[0], rows.val[1]);
const int32x4_t b0 = vqabsq_s32(vaddq_s32(a0, a1)); // abs(a0 + a1)
const int32x4_t b1 = vqabsq_s32(vaddq_s32(a3, a2)); // abs(a3 + a2)
const int32x4_t b2 = vabdq_s32(a3, a2); // abs(a3 - a2)
const int32x4_t b3 = vabdq_s32(a0, a1); // abs(a0 - a1)
const int32x4x4_t res = { { b0, b1, b2, b3 } };
return res;
static WEBP_INLINE int16x8x4_t DistoVerticalPass(int16x8x4_t q4_in) {
const int16x8_t q_a0 = vaddq_s16(q4_in.val[0], q4_in.val[2]);
const int16x8_t q_a1 = vaddq_s16(q4_in.val[1], q4_in.val[3]);
const int16x8_t q_a2 = vsubq_s16(q4_in.val[1], q4_in.val[3]);
const int16x8_t q_a3 = vsubq_s16(q4_in.val[0], q4_in.val[2]);
q4_in.val[0] = vaddq_s16(q_a0, q_a1);
q4_in.val[1] = vaddq_s16(q_a3, q_a2);
q4_in.val[2] = vabdq_s16(q_a3, q_a2);
q4_in.val[3] = vabdq_s16(q_a0, q_a1);
q4_in.val[0] = vabsq_s16(q4_in.val[0]);
q4_in.val[1] = vabsq_s16(q4_in.val[1]);
return q4_in;
}
// Calculate the weighted sum of the rows in 'b'.
static WEBP_INLINE int64x1_t DistoSum(const int32x4x4_t b,
const int32x4_t w0, const int32x4_t w1,
const int32x4_t w2, const int32x4_t w3) {
const int32x4_t s0 = vmulq_s32(w0, b.val[0]);
const int32x4_t s1 = vmlaq_s32(s0, w1, b.val[1]);
const int32x4_t s2 = vmlaq_s32(s1, w2, b.val[2]);
const int32x4_t s3 = vmlaq_s32(s2, w3, b.val[3]);
const int64x2_t sum1 = vpaddlq_s32(s3);
const int64x1_t sum2 = vadd_s64(vget_low_s64(sum1), vget_high_s64(sum1));
return sum2;
static WEBP_INLINE int16x4x4_t DistoLoadW(const uint16_t* w) {
const uint16x8_t q_w07 = vld1q_u16(&w[0]);
const uint16x8_t q_w8f = vld1q_u16(&w[8]);
int16x4x4_t d4_w;
INIT_VECTOR4(d4_w,
vget_low_s16(vreinterpretq_s16_u16(q_w07)),
vget_high_s16(vreinterpretq_s16_u16(q_w07)),
vget_low_s16(vreinterpretq_s16_u16(q_w8f)),
vget_high_s16(vreinterpretq_s16_u16(q_w8f)));
return d4_w;
}
static WEBP_INLINE int32x2_t DistoSum(const int16x8x4_t q4_in,
const int16x4x4_t d4_w) {
int32x2_t d_sum;
// sum += w[ 0] * abs(b0);
// sum += w[ 4] * abs(b1);
// sum += w[ 8] * abs(b2);
// sum += w[12] * abs(b3);
int32x4_t q_sum0 = vmull_s16(d4_w.val[0], vget_low_s16(q4_in.val[0]));
int32x4_t q_sum1 = vmull_s16(d4_w.val[1], vget_low_s16(q4_in.val[1]));
int32x4_t q_sum2 = vmull_s16(d4_w.val[2], vget_low_s16(q4_in.val[2]));
int32x4_t q_sum3 = vmull_s16(d4_w.val[3], vget_low_s16(q4_in.val[3]));
q_sum0 = vmlsl_s16(q_sum0, d4_w.val[0], vget_high_s16(q4_in.val[0]));
q_sum1 = vmlsl_s16(q_sum1, d4_w.val[1], vget_high_s16(q4_in.val[1]));
q_sum2 = vmlsl_s16(q_sum2, d4_w.val[2], vget_high_s16(q4_in.val[2]));
q_sum3 = vmlsl_s16(q_sum3, d4_w.val[3], vget_high_s16(q4_in.val[3]));
q_sum0 = vaddq_s32(q_sum0, q_sum1);
q_sum2 = vaddq_s32(q_sum2, q_sum3);
q_sum2 = vaddq_s32(q_sum0, q_sum2);
d_sum = vpadd_s32(vget_low_s32(q_sum2), vget_high_s32(q_sum2));
d_sum = vpadd_s32(d_sum, d_sum);
return d_sum;
}
#define LOAD_LANE_32b(src, VALUE, LANE) \
(VALUE) = vld1q_lane_u32((const uint32_t*)(src), (VALUE), (LANE))
(VALUE) = vld1_lane_u32((const uint32_t*)(src), (VALUE), (LANE))
// Hadamard transform
// Returns the weighted sum of the absolute value of transformed coefficients.
static int Disto4x4(const uint8_t* const a, const uint8_t* const b,
const uint16_t* const w) {
uint32x4_t d0d1 = { 0, 0, 0, 0 };
uint32x4_t d2d3 = { 0, 0, 0, 0 };
LOAD_LANE_32b(a + 0 * BPS, d0d1, 0); // a00 a01 a02 a03
LOAD_LANE_32b(a + 1 * BPS, d0d1, 1); // a10 a11 a12 a13
LOAD_LANE_32b(b + 0 * BPS, d0d1, 2); // b00 b01 b02 b03
LOAD_LANE_32b(b + 1 * BPS, d0d1, 3); // b10 b11 b12 b13
LOAD_LANE_32b(a + 2 * BPS, d2d3, 0); // a20 a21 a22 a23
LOAD_LANE_32b(a + 3 * BPS, d2d3, 1); // a30 a31 a32 a33
LOAD_LANE_32b(b + 2 * BPS, d2d3, 2); // b20 b21 b22 b23
LOAD_LANE_32b(b + 3 * BPS, d2d3, 3); // b30 b31 b32 b33
uint32x2_t d_in_ab_0123 = vdup_n_u32(0);
uint32x2_t d_in_ab_4567 = vdup_n_u32(0);
uint32x2_t d_in_ab_89ab = vdup_n_u32(0);
uint32x2_t d_in_ab_cdef = vdup_n_u32(0);
uint8x8x4_t d4_in;
// load data a, b
LOAD_LANE_32b(a + 0 * BPS, d_in_ab_0123, 0);
LOAD_LANE_32b(a + 1 * BPS, d_in_ab_4567, 0);
LOAD_LANE_32b(a + 2 * BPS, d_in_ab_89ab, 0);
LOAD_LANE_32b(a + 3 * BPS, d_in_ab_cdef, 0);
LOAD_LANE_32b(b + 0 * BPS, d_in_ab_0123, 1);
LOAD_LANE_32b(b + 1 * BPS, d_in_ab_4567, 1);
LOAD_LANE_32b(b + 2 * BPS, d_in_ab_89ab, 1);
LOAD_LANE_32b(b + 3 * BPS, d_in_ab_cdef, 1);
INIT_VECTOR4(d4_in,
vreinterpret_u8_u32(d_in_ab_0123),
vreinterpret_u8_u32(d_in_ab_4567),
vreinterpret_u8_u32(d_in_ab_89ab),
vreinterpret_u8_u32(d_in_ab_cdef));
{
// a00 a01 a20 a21 a10 a11 a30 a31 b00 b01 b20 b21 b10 b11 b30 b31
// a02 a03 a22 a23 a12 a13 a32 a33 b02 b03 b22 b23 b12 b13 b32 b33
const uint16x8x2_t tmp =
vtrnq_u16(vreinterpretq_u16_u32(d0d1), vreinterpretq_u16_u32(d2d3));
const uint8x16_t d0d1u8 = vreinterpretq_u8_u16(tmp.val[0]);
const uint8x16_t d2d3u8 = vreinterpretq_u8_u16(tmp.val[1]);
const int32x4x4_t hpass_a = DistoHorizontalPass(vget_low_u8(d0d1u8),
vget_low_u8(d2d3u8));
const int32x4x4_t hpass_b = DistoHorizontalPass(vget_high_u8(d0d1u8),
vget_high_u8(d2d3u8));
const int32x4x4_t tmp_a = DistoTranspose4x4(hpass_a);
const int32x4x4_t tmp_b = DistoTranspose4x4(hpass_b);
const int32x4x4_t vpass_a = DistoVerticalPass(tmp_a);
const int32x4x4_t vpass_b = DistoVerticalPass(tmp_b);
const int32x4_t w0 = ConvertU16ToS32(vld1_u16(w + 0));
const int32x4_t w1 = ConvertU16ToS32(vld1_u16(w + 4));
const int32x4_t w2 = ConvertU16ToS32(vld1_u16(w + 8));
const int32x4_t w3 = ConvertU16ToS32(vld1_u16(w + 12));
const int64x1_t sum1 = DistoSum(vpass_a, w0, w1, w2, w3);
const int64x1_t sum2 = DistoSum(vpass_b, w0, w1, w2, w3);
const int32x2_t diff = vabd_s32(vreinterpret_s32_s64(sum1),
vreinterpret_s32_s64(sum2));
const int32x2_t res = vshr_n_s32(diff, 5);
return vget_lane_s32(res, 0);
// horizontal pass
const uint8x8x4_t d4_t = DistoTranspose4x4U8(d4_in);
const int16x8x4_t q4_h = DistoHorizontalPass(d4_t);
const int16x4x4_t d4_w = DistoLoadW(w);
// vertical pass
const int16x8x4_t q4_t = DistoTranspose4x4S16(q4_h);
const int16x8x4_t q4_v = DistoVerticalPass(q4_t);
int32x2_t d_sum = DistoSum(q4_v, d4_w);
// abs(sum2 - sum1) >> 5
d_sum = vabs_s32(d_sum);
d_sum = vshr_n_s32(d_sum, 5);
return vget_lane_s32(d_sum, 0);
}
}
#undef LOAD_LANE_32b
#else
// Hadamard transform
// Returns the weighted sum of the absolute value of transformed coefficients.
static int Disto4x4(const uint8_t* const a, const uint8_t* const b,
const uint16_t* const w) {
const int kBPS = BPS;
const uint8_t* A = a;
const uint8_t* B = b;
const uint16_t* W = w;
int sum;
__asm__ volatile (
"vld1.32 d0[0], [%[a]], %[kBPS] \n"
"vld1.32 d0[1], [%[a]], %[kBPS] \n"
"vld1.32 d2[0], [%[a]], %[kBPS] \n"
"vld1.32 d2[1], [%[a]] \n"
"vld1.32 d1[0], [%[b]], %[kBPS] \n"
"vld1.32 d1[1], [%[b]], %[kBPS] \n"
"vld1.32 d3[0], [%[b]], %[kBPS] \n"
"vld1.32 d3[1], [%[b]] \n"
// a d0/d2, b d1/d3
// d0/d1: 01 01 01 01
// d2/d3: 23 23 23 23
// But: it goes 01 45 23 67
// Notice the middle values are transposed
"vtrn.16 q0, q1 \n"
// {a0, a1} = {in[0] + in[2], in[1] + in[3]}
"vaddl.u8 q2, d0, d2 \n"
"vaddl.u8 q10, d1, d3 \n"
// {a3, a2} = {in[0] - in[2], in[1] - in[3]}
"vsubl.u8 q3, d0, d2 \n"
"vsubl.u8 q11, d1, d3 \n"
// tmp[0] = a0 + a1
"vpaddl.s16 q0, q2 \n"
"vpaddl.s16 q8, q10 \n"
// tmp[1] = a3 + a2
"vpaddl.s16 q1, q3 \n"
"vpaddl.s16 q9, q11 \n"
// No pair subtract
// q2 = {a0, a3}
// q3 = {a1, a2}
"vtrn.16 q2, q3 \n"
"vtrn.16 q10, q11 \n"
// {tmp[3], tmp[2]} = {a0 - a1, a3 - a2}
"vsubl.s16 q12, d4, d6 \n"
"vsubl.s16 q13, d5, d7 \n"
"vsubl.s16 q14, d20, d22 \n"
"vsubl.s16 q15, d21, d23 \n"
// separate tmp[3] and tmp[2]
// q12 = tmp[3]
// q13 = tmp[2]
"vtrn.32 q12, q13 \n"
"vtrn.32 q14, q15 \n"
// Transpose tmp for a
"vswp d1, d26 \n" // vtrn.64
"vswp d3, d24 \n" // vtrn.64
"vtrn.32 q0, q1 \n"
"vtrn.32 q13, q12 \n"
// Transpose tmp for b
"vswp d17, d30 \n" // vtrn.64
"vswp d19, d28 \n" // vtrn.64
"vtrn.32 q8, q9 \n"
"vtrn.32 q15, q14 \n"
// The first Q register is a, the second b.
// q0/8 tmp[0-3]
// q13/15 tmp[4-7]
// q1/9 tmp[8-11]
// q12/14 tmp[12-15]
// These are still in 01 45 23 67 order. We fix it easily in the addition
// case but the subtraction propagates them.
"vswp d3, d27 \n"
"vswp d19, d31 \n"
// a0 = tmp[0] + tmp[8]
"vadd.s32 q2, q0, q1 \n"
"vadd.s32 q3, q8, q9 \n"
// a1 = tmp[4] + tmp[12]
"vadd.s32 q10, q13, q12 \n"
"vadd.s32 q11, q15, q14 \n"
// a2 = tmp[4] - tmp[12]
"vsub.s32 q13, q13, q12 \n"
"vsub.s32 q15, q15, q14 \n"
// a3 = tmp[0] - tmp[8]
"vsub.s32 q0, q0, q1 \n"
"vsub.s32 q8, q8, q9 \n"
// b0 = a0 + a1
"vadd.s32 q1, q2, q10 \n"
"vadd.s32 q9, q3, q11 \n"
// b1 = a3 + a2
"vadd.s32 q12, q0, q13 \n"
"vadd.s32 q14, q8, q15 \n"
// b2 = a3 - a2
"vsub.s32 q0, q0, q13 \n"
"vsub.s32 q8, q8, q15 \n"
// b3 = a0 - a1
"vsub.s32 q2, q2, q10 \n"
"vsub.s32 q3, q3, q11 \n"
"vld1.64 {q10, q11}, [%[w]] \n"
// abs(b0)
"vabs.s32 q1, q1 \n"
"vabs.s32 q9, q9 \n"
// abs(b1)
"vabs.s32 q12, q12 \n"
"vabs.s32 q14, q14 \n"
// abs(b2)
"vabs.s32 q0, q0 \n"
"vabs.s32 q8, q8 \n"
// abs(b3)
"vabs.s32 q2, q2 \n"
"vabs.s32 q3, q3 \n"
// expand w before using.
"vmovl.u16 q13, d20 \n"
"vmovl.u16 q15, d21 \n"
// w[0] * abs(b0)
"vmul.u32 q1, q1, q13 \n"
"vmul.u32 q9, q9, q13 \n"
// w[4] * abs(b1)
"vmla.u32 q1, q12, q15 \n"
"vmla.u32 q9, q14, q15 \n"
// expand w before using.
"vmovl.u16 q13, d22 \n"
"vmovl.u16 q15, d23 \n"
// w[8] * abs(b1)
"vmla.u32 q1, q0, q13 \n"
"vmla.u32 q9, q8, q13 \n"
// w[12] * abs(b1)
"vmla.u32 q1, q2, q15 \n"
"vmla.u32 q9, q3, q15 \n"
// Sum the arrays
"vpaddl.u32 q1, q1 \n"
"vpaddl.u32 q9, q9 \n"
"vadd.u64 d2, d3 \n"
"vadd.u64 d18, d19 \n"
// Hadamard transform needs 4 bits of extra precision (2 bits in each
// direction) for dynamic raw. Weights w[] are 16bits at max, so the maximum
// precision for coeff is 8bit of input + 4bits of Hadamard transform +
// 16bits for w[] + 2 bits of abs() summation.
//
// This uses a maximum of 31 bits (signed). Discarding the top 32 bits is
// A-OK.
// sum2 - sum1
"vsub.u32 d0, d2, d18 \n"
// abs(sum2 - sum1)
"vabs.s32 d0, d0 \n"
// abs(sum2 - sum1) >> 5
"vshr.u32 d0, #5 \n"
// It would be better to move the value straight into r0 but I'm not
// entirely sure how this works with inline assembly.
"vmov.32 %[sum], d0[0] \n"
: [sum] "=r"(sum), [a] "+r"(A), [b] "+r"(B), [w] "+r"(W)
: [kBPS] "r"(kBPS)
: "memory", "q0", "q1", "q2", "q3", "q4", "q5", "q6", "q7", "q8", "q9",
"q10", "q11", "q12", "q13", "q14", "q15" // clobbered
) ;
return sum;
}
#endif // USE_INTRINSICS
static int Disto16x16(const uint8_t* const a, const uint8_t* const b,
const uint16_t* const w) {
int D = 0;