// Copyright 2011 Google Inc.
//
// This code is licensed under the same terms as WebM:
// Software License Agreement: http://www.webmproject.org/license/software/
// Additional IP Rights Grant: http://www.webmproject.org/license/additional/
// -----------------------------------------------------------------------------
//
// frame coding and analysis
//
// Author: Skal (pascal.massimino@gmail.com)
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <math.h>
#include "vp8enci.h"
#include "cost.h"
#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif
#define SEGMENT_VISU 0
#define DEBUG_SEARCH 0 // useful to track search convergence
// On-the-fly info about the current set of residuals. Handy to avoid
// passing zillions of params.
typedef struct {
int first;
int last;
const int16_t* coeffs;
int coeff_type;
ProbaArray* prob;
StatsArray* stats;
CostArray* cost;
} VP8Residual;
//-----------------------------------------------------------------------------
// Tables for level coding
const uint8_t VP8EncBands[16 + 1] = {
0, 1, 2, 3, 6, 4, 5, 6, 6, 6, 6, 6, 6, 6, 6, 7,
0 // sentinel
};
static const uint8_t kCat3[] = { 173, 148, 140 };
static const uint8_t kCat4[] = { 176, 155, 140, 135 };
static const uint8_t kCat5[] = { 180, 157, 141, 134, 130 };
static const uint8_t kCat6[] =
{ 254, 254, 243, 230, 196, 177, 153, 140, 133, 130, 129 };
//-----------------------------------------------------------------------------
// Reset the statistics about: number of skips, token proba, level cost,...
static void ResetStats(VP8Encoder* const enc, int precalc_cost) {
VP8Proba* const proba = &enc->proba_;
if (precalc_cost) VP8CalculateLevelCosts(proba);
proba->nb_skip_ = 0;
}
//-----------------------------------------------------------------------------
// Skip decision probability
static int CalcSkipProba(uint64_t nb, uint64_t total) {
return (int)(total ? (total - nb) * 255 / total : 255);
}
// Returns the bit-cost for coding the skip probability.
static int FinalizeSkipProba(VP8Encoder* const enc) {
VP8Proba* const proba = &enc->proba_;
const int nb_mbs = enc->mb_w_ * enc->mb_h_;
const int nb_events = proba->nb_skip_;
int size;
proba->skip_proba_ = CalcSkipProba(nb_events, nb_mbs);
proba->use_skip_proba_ = (proba->skip_proba_ < 250);
size = 256; // 'use_skip_proba' bit
if (proba->use_skip_proba_) {
size += nb_events * VP8BitCost(1, proba->skip_proba_)
+ (nb_mbs - nb_events) * VP8BitCost(0, proba->skip_proba_);
size += 8 * 256; // cost of signaling the skip_proba_ itself.
}
return size;
}
//-----------------------------------------------------------------------------
// Recording of token probabilities.
static void ResetTokenStats(VP8Encoder* const enc) {
VP8Proba* const proba = &enc->proba_;
memset(proba->stats_, 0, sizeof(proba->stats_));
}
// Record proba context used
static int Record(int bit, uint64_t* const stats) {
stats[0] += bit;
stats[1] += 1;
return bit;
}
// We keep the table free variant around for reference, in case.
#define USE_LEVEL_CODE_TABLE
// Simulate block coding, but only record statistics.
// Note: no need to record the fixed probas.
static int RecordCoeffs(int ctx, VP8Residual* res) {
int n = res->first;
uint64_t (*s)[2] = res->stats[VP8EncBands[n]][ctx];
if (!Record(res->last >= 0, s[0])) {
return 0;
}
while (1) {
int v = res->coeffs[n++];
if (!Record(v != 0, s[1])) {
s = res->stats[VP8EncBands[n]][0];
continue;
}
if (!Record(2u < (unsigned int)(v + 1), s[2])) { // v = -1 or 1
s = res->stats[VP8EncBands[n]][1];
} else {
v = abs(v);
#if !defined(USE_LEVEL_CODE_TABLE)
if (!Record(v > 4, s[3])) {
if (Record(v != 2, s[4]))
Record(v == 4, s[5]);
} else if (!Record(v > 10, s[6])) {
Record(v > 6, s[7]);
} else if (!Record((v >= 3 + (8 << 2)), s[8])) {
Record((v >= 3 + (8 << 1)), s[9]);
} else {
Record((v >= 3 + (8 << 3)), s[10]);
}
#else
if (v > MAX_VARIABLE_LEVEL)
v = MAX_VARIABLE_LEVEL;
{
const int bits = VP8LevelCodes[v - 1][1];
int pattern = VP8LevelCodes[v - 1][0];
int i;
for (i = 0; (pattern >>= 1) != 0; ++i) {
const int mask = 2 << i;
if (pattern & 1) Record(!!(bits & mask), s[3 + i]);
}
}
#endif
s = res->stats[VP8EncBands[n]][2];
}
if (n == 16 || !Record(n <= res->last, s[0])) {
return 1;
}
}
}
// Collect statistics and deduce probabilities for next coding pass.
// Return the total bit-cost for coding the probability updates.
static int CalcTokenProba(uint64_t nb, uint64_t total) {
return (int)(nb ? ((total - nb) * 255 + total / 2) / total : 255);
}
static int FinalizeTokenProbas(VP8Encoder* const enc) {
VP8Proba* const proba = &enc->proba_;
int size = 0;
int t, b, c, p;
for (t = 0; t < NUM_TYPES; ++t) {
for (b = 0; b < NUM_BANDS; ++b) {
for (c = 0; c < NUM_CTX; ++c) {
for (p = 0; p < NUM_PROBAS; ++p) {
const uint64_t* const cnt = proba->stats_[t][b][c][p];
const int update_proba = VP8CoeffsUpdateProba[t][b][c][p];
const int old_p = VP8CoeffsProba0[t][b][c][p];
const int new_p = CalcTokenProba(cnt[0], cnt[1]);
const uint64_t old_cost = VP8BranchCost(cnt[0], cnt[1], old_p)
+ VP8BitCost(0, update_proba);
const uint64_t new_cost = VP8BranchCost(cnt[0], cnt[1], new_p)
+ VP8BitCost(1, update_proba) + 8 * 256;
const int use_new_p = (old_cost > new_cost);
size += VP8BitCost(use_new_p, update_proba);
if (use_new_p) { // only use proba that seem meaningful enough.
proba->coeffs_[t][b][c][p] = new_p;
size += 8 * 256;
} else {
proba->coeffs_[t][b][c][p] = old_p;
}
}
}
}
}
return size;
}
//-----------------------------------------------------------------------------
// helper functions for residuals struct VP8Residual.
static void InitResidual(int first, int coeff_type,
VP8Encoder* const enc, VP8Residual* const res) {
res->coeff_type = coeff_type;
res->prob = enc->proba_.coeffs_[coeff_type];
res->stats = enc->proba_.stats_[coeff_type];
res->cost = enc->proba_.level_cost_[coeff_type];
res->first = first;
}
static void SetResidualCoeffs(const int16_t* const coeffs,
VP8Residual* const res) {
int n;
res->last = -1;
for (n = 15; n >= res->first; --n) {
if (coeffs[n]) {
res->last = n;
break;
}
}
res->coeffs = coeffs;
}
//-----------------------------------------------------------------------------
// Mode costs
static int GetResidualCost(int ctx, const VP8Residual* const res) {
int n = res->first;
const uint8_t* p = res->prob[VP8EncBands[n]][ctx];
const uint16_t *t = res->cost[VP8EncBands[n]][ctx];
int cost;
cost = VP8BitCost(res->last >= 0, p[0]);
if (res->last < 0) {
return cost;
}
while (n <= res->last) {
const int v = res->coeffs[n++];
if (v == 0) {
cost += VP8LevelCost(t, 0);
p = res->prob[VP8EncBands[n]][0];
t = res->cost[VP8EncBands[n]][0];
continue;
} else if (2u >= (unsigned int)(v + 1)) { // v = -1 or 1
cost += VP8LevelCost(t, 1);
p = res->prob[VP8EncBands[n]][1];
t = res->cost[VP8EncBands[n]][1];
} else {
cost += VP8LevelCost(t, abs(v));
p = res->prob[VP8EncBands[n]][2];
t = res->cost[VP8EncBands[n]][2];
}
if (n < 16) {
cost += VP8BitCost(n <= res->last, p[0]);
}
}
return cost;
}
int VP8GetCostLuma4(VP8EncIterator* const it, const int16_t levels[16]) {
const int x = (it->i4_ & 3), y = (it->i4_ >> 2);
VP8Residual res;
int R = 0;
int ctx;
InitResidual(0, 3, it->enc_, &res);
ctx = it->top_nz_[x] + it->left_nz_[y];
SetResidualCoeffs(levels, &res);
R += GetResidualCost(ctx, &res);
return R;
}
int VP8GetCostLuma16(VP8EncIterator* const it, const VP8ModeScore* const rd) {
VP8Residual res;
int x, y;
int R = 0;
VP8IteratorNzToBytes(it); // re-import the non-zero context
// DC
InitResidual(0, 1, it->enc_, &res);
SetResidualCoeffs(rd->y_dc_levels, &res);
R += GetResidualCost(it->top_nz_[8] + it->left_nz_[8], &res);
// AC
InitResidual(1, 0, it->enc_, &res);
for (y = 0; y < 4; ++y) {
for (x = 0; x < 4; ++x) {
const int ctx = it->top_nz_[x] + it->left_nz_[y];
SetResidualCoeffs(rd->y_ac_levels[x + y * 4], &res);
R += GetResidualCost(ctx, &res);
it->top_nz_[x] = it->left_nz_[y] = (res.last >= 0);
}
}
return R;
}
int VP8GetCostUV(VP8EncIterator* const it, const VP8ModeScore* const rd) {
VP8Residual res;
int ch, x, y;
int R = 0;
VP8IteratorNzToBytes(it); // re-import the non-zero context
InitResidual(0, 2, it->enc_, &res);
for (ch = 0; ch <= 2; ch += 2) {
for (y = 0; y < 2; ++y) {
for (x = 0; x < 2; ++x) {
const int ctx = it->top_nz_[4 + ch + x] + it->left_nz_[4 + ch + y];
SetResidualCoeffs(rd->uv_levels[ch * 2 + x + y * 2], &res);
R += GetResidualCost(ctx, &res);
it->top_nz_[4 + ch + x] = it->left_nz_[4 + ch + y] = (res.last >= 0);
}
}
}
return R;
}
//-----------------------------------------------------------------------------
// Coefficient coding
static int PutCoeffs(VP8BitWriter* const bw, int ctx, const VP8Residual* res) {
int n = res->first;
const uint8_t* p = res->prob[VP8EncBands[n]][ctx];
if (!VP8PutBit(bw, res->last >= 0, p[0])) {
return 0;
}
while (n < 16) {
const int c = res->coeffs[n++];
const int sign = c < 0;
int v = sign ? -c : c;
if (!VP8PutBit(bw, v != 0, p[1])) {
p = res->prob[VP8EncBands[n]][0];
continue;
}
if (!VP8PutBit(bw, v > 1, p[2])) {
p = res->prob[VP8EncBands[n]][1];
} else {
if (!VP8PutBit(bw, v > 4, p[3])) {
if (VP8PutBit(bw, v != 2, p[4]))
VP8PutBit(bw, v == 4, p[5]);
} else if (!VP8PutBit(bw, v > 10, p[6])) {
if (!VP8PutBit(bw, v > 6, p[7])) {
VP8PutBit(bw, v == 6, 159);
} else {
VP8PutBit(bw, v >= 9, 165);
VP8PutBit(bw, !(v & 1), 145);
}
} else {
int mask;
const uint8_t* tab;
if (v < 3 + (8 << 1)) { // kCat3 (3b)
VP8PutBit(bw, 0, p[8]);
VP8PutBit(bw, 0, p[9]);
v -= 3 + (8 << 0);
mask = 1 << 2;
tab = kCat3;
} else if (v < 3 + (8 << 2)) { // kCat4 (4b)
VP8PutBit(bw, 0, p[8]);
VP8PutBit(bw, 1, p[9]);
v -= 3 + (8 << 1);
mask = 1 << 3;
tab = kCat4;
} else if (v < 3 + (8 << 3)) { // kCat5 (5b)
VP8PutBit(bw, 1, p[8]);
VP8PutBit(bw, 0, p[10]);
v -= 3 + (8 << 2);
mask = 1 << 4;
tab = kCat5;
} else { // kCat6 (11b)
VP8PutBit(bw, 1, p[8]);
VP8PutBit(bw, 1, p[10]);
v -= 3 + (8 << 3);
mask = 1 << 10;
tab = kCat6;
}
while (mask) {
VP8PutBit(bw, !!(v & mask), *tab++);
mask >>= 1;
}
}
p = res->prob[VP8EncBands[n]][2];
}
VP8PutBitUniform(bw, sign);
if (n == 16 || !VP8PutBit(bw, n <= res->last, p[0])) {
return 1; // EOB
}
}
return 1;
}
static void CodeResiduals(VP8BitWriter* const bw,
VP8EncIterator* const it,
const VP8ModeScore* const rd) {
int x, y, ch;
VP8Residual res;
uint64_t pos1, pos2, pos3;
const int i16 = (it->mb_->type_ == 1);
const int segment = it->mb_->segment_;
VP8IteratorNzToBytes(it);
pos1 = VP8BitWriterPos(bw);
if (i16) {
InitResidual(0, 1, it->enc_, &res);
SetResidualCoeffs(rd->y_dc_levels, &res);
it->top_nz_[8] = it->left_nz_[8] =
PutCoeffs(bw, it->top_nz_[8] + it->left_nz_[8], &res);
InitResidual(1, 0, it->enc_, &res);
} else {
InitResidual(0, 3, it->enc_, &res);
}
// luma-AC
for (y = 0; y < 4; ++y) {
for (x = 0; x < 4; ++x) {
const int ctx = it->top_nz_[x] + it->left_nz_[y];
SetResidualCoeffs(rd->y_ac_levels[x + y * 4], &res);
it->top_nz_[x] = it->left_nz_[y] = PutCoeffs(bw, ctx, &res);
}
}
pos2 = VP8BitWriterPos(bw);
// U/V
InitResidual(0, 2, it->enc_, &res);
for (ch = 0; ch <= 2; ch += 2) {
for (y = 0; y < 2; ++y) {
for (x = 0; x < 2; ++x) {
const int ctx = it->top_nz_[4 + ch + x] + it->left_nz_[4 + ch + y];
SetResidualCoeffs(rd->uv_levels[ch * 2 + x + y * 2], &res);
it->top_nz_[4 + ch + x] = it->left_nz_[4 + ch + y] =
PutCoeffs(bw, ctx, &res);
}
}
}
pos3 = VP8BitWriterPos(bw);
it->luma_bits_ = pos2 - pos1;
it->uv_bits_ = pos3 - pos2;
it->bit_count_[segment][i16] += it->luma_bits_;
it->bit_count_[segment][2] += it->uv_bits_;
VP8IteratorBytesToNz(it);
}
// Same as CodeResiduals, but doesn't actually write anything.
// Instead, it just records the event distribution.
static void RecordResiduals(VP8EncIterator* const it,
const VP8ModeScore* const rd) {
int x, y, ch;
VP8Residual res;
VP8IteratorNzToBytes(it);
if (it->mb_->type_ == 1) { // i16x16
InitResidual(0, 1, it->enc_, &res);
SetResidualCoeffs(rd->y_dc_levels, &res);
it->top_nz_[8] = it->left_nz_[8] =
RecordCoeffs(it->top_nz_[8] + it->left_nz_[8], &res);
InitResidual(1, 0, it->enc_, &res);
} else {
InitResidual(0, 3, it->enc_, &res);
}
// luma-AC
for (y = 0; y < 4; ++y) {
for (x = 0; x < 4; ++x) {
const int ctx = it->top_nz_[x] + it->left_nz_[y];
SetResidualCoeffs(rd->y_ac_levels[x + y * 4], &res);
it->top_nz_[x] = it->left_nz_[y] = RecordCoeffs(ctx, &res);
}
}
// U/V
InitResidual(0, 2, it->enc_, &res);
for (ch = 0; ch <= 2; ch += 2) {
for (y = 0; y < 2; ++y) {
for (x = 0; x < 2; ++x) {
const int ctx = it->top_nz_[4 + ch + x] + it->left_nz_[4 + ch + y];
SetResidualCoeffs(rd->uv_levels[ch * 2 + x + y * 2], &res);
it->top_nz_[4 + ch + x] = it->left_nz_[4 + ch + y] =
RecordCoeffs(ctx, &res);
}
}
}
VP8IteratorBytesToNz(it);
}
//-----------------------------------------------------------------------------
// ExtraInfo map / Debug function
#if SEGMENT_VISU
static void SetBlock(uint8_t* p, int value, int size) {
int y;
for (y = 0; y < size; ++y) {
memset(p, value, size);
p += BPS;
}
}
#endif
static void ResetSSE(VP8Encoder* const enc) {
memset(enc->sse_, 0, sizeof(enc->sse_));
enc->sse_count_ = 0;
}
static void StoreSSE(const VP8EncIterator* const it) {
VP8Encoder* const enc = it->enc_;
const uint8_t* const in = it->yuv_in_;
const uint8_t* const out = it->yuv_out_;
// Note: not totally accurate at boundary. And doesn't include in-loop filter.
enc->sse_[0] += VP8SSE16x16(in + Y_OFF, out + Y_OFF);
enc->sse_[1] += VP8SSE8x8(in + U_OFF, out + U_OFF);
enc->sse_[2] += VP8SSE8x8(in + V_OFF, out + V_OFF);
enc->sse_count_ += 16 * 16;
}
static void StoreSideInfo(const VP8EncIterator* const it) {
VP8Encoder* const enc = it->enc_;
const VP8MBInfo* const mb = it->mb_;
WebPPicture* const pic = enc->pic_;
if (pic->stats) {
StoreSSE(it);
enc->block_count_[0] += (mb->type_ == 0);
enc->block_count_[1] += (mb->type_ == 1);
enc->block_count_[2] += (mb->skip_ != 0);
}
if (pic->extra_info) {
uint8_t* const info = &pic->extra_info[it->x_ + it->y_ * enc->mb_w_];
switch(pic->extra_info_type) {
case 1: *info = mb->type_; break;
case 2: *info = mb->segment_; break;
case 3: *info = enc->dqm_[mb->segment_].quant_; break;
case 4: *info = (mb->type_ == 1) ? it->preds_[0] : 0xff; break;
case 5: *info = mb->uv_mode_; break;
case 6: {
const int b = (int)((it->luma_bits_ + it->uv_bits_ + 7) >> 3);
*info = (b > 255) ? 255 : b; break;
}
default: *info = 0; break;
};
}
#if SEGMENT_VISU // visualize segments and prediction modes
SetBlock(it->yuv_out_ + Y_OFF, mb->segment_ * 64, 16);
SetBlock(it->yuv_out_ + U_OFF, it->preds_[0] * 64, 8);
SetBlock(it->yuv_out_ + V_OFF, mb->uv_mode_ * 64, 8);
#endif
}
//-----------------------------------------------------------------------------
// Main loops
//
// VP8EncLoop(): does the final bitstream coding.
static void ResetAfterSkip(VP8EncIterator* const it) {
if (it->mb_->type_ == 1) {
*it->nz_ = 0; // reset all predictors
it->left_nz_[8] = 0;
} else {
*it->nz_ &= (1 << 24); // preserve the dc_nz bit
}
}
int VP8EncLoop(VP8Encoder* const enc) {
int i, s, p;
VP8EncIterator it;
VP8ModeScore info;
const int dont_use_skip = !enc->proba_.use_skip_proba_;
const int rd_opt = enc->rd_opt_level_;
const int kAverageBytesPerMB = 5; // TODO: have a kTable[quality/10]
const int bytes_per_parts =
enc->mb_w_ * enc->mb_h_ * kAverageBytesPerMB / enc->num_parts_;
// Initialize the bit-writers
for (p = 0; p < enc->num_parts_; ++p) {
VP8BitWriterInit(enc->parts_ + p, bytes_per_parts);
}
ResetStats(enc, rd_opt != 0);
ResetSSE(enc);
VP8IteratorInit(enc, &it);
VP8InitFilter(&it);
do {
VP8IteratorImport(&it);
// Warning! order is important: first call VP8Decimate() and
// *then* decide how to code the skip decision if there's one.
if (!VP8Decimate(&it, &info, rd_opt) || dont_use_skip) {
CodeResiduals(it.bw_, &it, &info);
} else { // reset predictors after a skip
ResetAfterSkip(&it);
}
#ifdef WEBP_EXPERIMENTAL_FEATURES
if (enc->has_alpha_) {
VP8EncCodeAlphaBlock(&it);
}
if (enc->use_layer_) {
VP8EncCodeLayerBlock(&it);
}
#endif
StoreSideInfo(&it);
VP8StoreFilterStats(&it);
VP8IteratorExport(&it);
} while (VP8IteratorNext(&it, it.yuv_out_));
VP8AdjustFilterStrength(&it);
// Finalize the partitions
for (p = 0; p < enc->num_parts_; ++p) {
VP8BitWriterFinish(enc->parts_ + p);
}
// and byte counters
if (enc->pic_->stats) {
for (i = 0; i <= 2; ++i) {
for (s = 0; s < NUM_MB_SEGMENTS; ++s) {
enc->residual_bytes_[i][s] = (int)((it.bit_count_[s][i] + 7) >> 3);
}
}
}
return 1;
}
//-----------------------------------------------------------------------------
// VP8StatLoop(): only collect statistics (number of skips, token usage, ...)
// This is used for deciding optimal probabilities. It also
// modifies the quantizer value if some target (size, PNSR)
// was specified.
#define kHeaderSizeEstimate (15 + 20 + 10) // TODO: fix better
static int OneStatPass(VP8Encoder* const enc, float q, int rd_opt, int nb_mbs,
float* const PSNR) {
VP8EncIterator it;
uint64_t size = 0;
uint64_t distortion = 0;
const uint64_t pixel_count = nb_mbs * 384;
// Make sure the quality parameter is inside valid bounds
if (q < 0.) {
q = 0;
} else if (q > 100.) {
q = 100;
}
VP8SetSegmentParams(enc, q); // setup segment quantizations and filters
ResetStats(enc, rd_opt != 0);
ResetTokenStats(enc);
VP8IteratorInit(enc, &it);
do {
VP8ModeScore info;
VP8IteratorImport(&it);
if (VP8Decimate(&it, &info, rd_opt)) {
// Just record the number of skips and act like skip_proba is not used.
enc->proba_.nb_skip_++;
}
RecordResiduals(&it, &info);
size += info.R;
distortion += info.D;
} while (VP8IteratorNext(&it, it.yuv_out_) && --nb_mbs > 0);
size += FinalizeSkipProba(enc);
size += FinalizeTokenProbas(enc);
size += enc->segment_hdr_.size_;
size = ((size + 1024) >> 11) + kHeaderSizeEstimate;
if (PSNR) {
*PSNR = (float)(10.* log10(255. * 255. * pixel_count / distortion));
}
return (int)size;
}
// successive refinement increments.
static const int dqs[] = { 20, 15, 10, 8, 6, 4, 2, 1, 0 };
int VP8StatLoop(VP8Encoder* const enc) {
const int do_search =
(enc->config_->target_size > 0 || enc->config_->target_PSNR > 0);
const int fast_probe = (enc->method_ < 2 && !do_search);
float q = enc->config_->quality;
int pass;
int nb_mbs;
// Fast mode: quick analysis pass over few mbs. Better than nothing.
nb_mbs = enc->mb_w_ * enc->mb_h_;
if (fast_probe && nb_mbs > 100) nb_mbs = 100;
// No target size: just do several pass without changing 'q'
if (!do_search) {
for (pass = 0; pass < enc->config_->pass; ++pass) {
const int rd_opt = (enc->method_ > 2);
OneStatPass(enc, q, rd_opt, nb_mbs, NULL);
}
return 1;
}
// binary search for a size close to target
for (pass = 0; pass < enc->config_->pass && (dqs[pass] > 0); ++pass) {
const int rd_opt = 1;
float PSNR;
int criterion;
const int size = OneStatPass(enc, q, rd_opt, nb_mbs, &PSNR);
#if DEBUG_SEARCH
printf("#%d size=%d PSNR=%.2f q=%.2f\n", pass, size, PSNR, q);
#endif
if (enc->config_->target_PSNR > 0) {
criterion = (PSNR < enc->config_->target_PSNR);
} else {
criterion = (size < enc->config_->target_size);
}
// dichotomize
if (criterion) {
q += dqs[pass];
} else {
q -= dqs[pass];
}
}
return 1;
}
//-----------------------------------------------------------------------------
#if defined(__cplusplus) || defined(c_plusplus)
} // extern "C"
#endif