drivers/media/platform/vivid/vivid-sdr-cap.c

   1 /*
   2  * vivid-sdr-cap.c - software defined radio support functions.
   3  *
   4  * Copyright 2014 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
   5  *
   6  * This program is free software; you may redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; version 2 of the License.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  11  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  12  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  13  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  14  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  15  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  16  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  17  * SOFTWARE.
  18  */
  19
  20 #include <linux/errno.h>
  21 #include <linux/kernel.h>
  22 #include <linux/delay.h>
  23 #include <linux/kthread.h>
  24 #include <linux/freezer.h>
  25 #include <linux/math64.h>
  26 #include <linux/videodev2.h>
  27 #include <linux/v4l2-dv-timings.h>
  28 #include <media/v4l2-common.h>
  29 #include <media/v4l2-event.h>
  30 #include <media/v4l2-dv-timings.h>
  31 #include <linux/fixp-arith.h>
  32
  33 #include "vivid-core.h"
  34 #include "vivid-ctrls.h"
  35 #include "vivid-sdr-cap.h"
  36
  37 /* stream formats */
  38 struct vivid_format {
  39         u32     pixelformat;
  40         u32     buffersize;
  41 };
  42
  43 /* format descriptions for capture and preview */
  44 static const struct vivid_format formats[] = {
  45         {
  46                 .pixelformat    = V4L2_SDR_FMT_CU8,
  47                 .buffersize     = SDR_CAP_SAMPLES_PER_BUF * 2,
  48         }, {
  49                 .pixelformat    = V4L2_SDR_FMT_CS8,
  50                 .buffersize     = SDR_CAP_SAMPLES_PER_BUF * 2,
  51         },
  52 };
  53
  54 static const unsigned int NUM_FORMATS = ARRAY_SIZE(formats);
  55
  56 static const struct v4l2_frequency_band bands_adc[] = {
  57         {
  58                 .tuner = 0,
  59                 .type = V4L2_TUNER_ADC,
  60                 .index = 0,
  61                 .capability = V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS,
  62                 .rangelow   =  300000,
  63                 .rangehigh  =  300000,
  64         },
  65         {
  66                 .tuner = 0,
  67                 .type = V4L2_TUNER_ADC,
  68                 .index = 1,
  69                 .capability = V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS,
  70                 .rangelow   =  900001,
  71                 .rangehigh  = 2800000,
  72         },
  73         {
  74                 .tuner = 0,
  75                 .type = V4L2_TUNER_ADC,
  76                 .index = 2,
  77                 .capability = V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS,
  78                 .rangelow   = 3200000,
  79                 .rangehigh  = 3200000,
  80         },
  81 };
  82
  83 /* ADC band midpoints */
  84 #define BAND_ADC_0 ((bands_adc[0].rangehigh + bands_adc[1].rangelow) / 2)
  85 #define BAND_ADC_1 ((bands_adc[1].rangehigh + bands_adc[2].rangelow) / 2)
  86
  87 static const struct v4l2_frequency_band bands_fm[] = {
  88         {
  89                 .tuner = 1,
  90                 .type = V4L2_TUNER_RF,
  91                 .index = 0,
  92                 .capability = V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS,
  93                 .rangelow   =    50000000,
  94                 .rangehigh  =  2000000000,
  95         },
  96 };
  97
  98 static void vivid_thread_sdr_cap_tick(struct vivid_dev *dev)
  99 {
 100         struct vivid_buffer *sdr_cap_buf = NULL;
 101
 102         dprintk(dev, 1, "SDR Capture Thread Tick\n");
 103
 104         /* Drop a certain percentage of buffers. */
 105         if (dev->perc_dropped_buffers &&
 106             prandom_u32_max(100) < dev->perc_dropped_buffers)
 107                 return;
 108
 109         spin_lock(&dev->slock);
 110         if (!list_empty(&dev->sdr_cap_active)) {
 111                 sdr_cap_buf = list_entry(dev->sdr_cap_active.next,
 112                                          struct vivid_buffer, list);
 113                 list_del(&sdr_cap_buf->list);
 114         }
 115         spin_unlock(&dev->slock);
 116
 117         if (sdr_cap_buf) {
 118                 sdr_cap_buf->vb.v4l2_buf.sequence = dev->sdr_cap_seq_count;
 119                 vivid_sdr_cap_process(dev, sdr_cap_buf);
 120                 v4l2_get_timestamp(&sdr_cap_buf->vb.v4l2_buf.timestamp);
 121                 sdr_cap_buf->vb.v4l2_buf.timestamp.tv_sec += dev->time_wrap_offset;
 122                 vb2_buffer_done(&sdr_cap_buf->vb, dev->dqbuf_error ?
 123                                 VB2_BUF_STATE_ERROR : VB2_BUF_STATE_DONE);
 124                 dev->dqbuf_error = false;
 125         }
 126 }
 127
 128 static int vivid_thread_sdr_cap(void *data)
 129 {
 130         struct vivid_dev *dev = data;
 131         u64 samples_since_start;
 132         u64 buffers_since_start;
 133         u64 next_jiffies_since_start;
 134         unsigned long jiffies_since_start;
 135         unsigned long cur_jiffies;
 136         unsigned wait_jiffies;
 137
 138         dprintk(dev, 1, "SDR Capture Thread Start\n");
 139
 140         set_freezable();
 141
 142         /* Resets frame counters */
 143         dev->sdr_cap_seq_offset = 0;
 144         if (dev->seq_wrap)
 145                 dev->sdr_cap_seq_offset = 0xffffff80U;
 146         dev->jiffies_sdr_cap = jiffies;
 147         dev->sdr_cap_seq_resync = false;
 148
 149         for (;;) {
 150                 try_to_freeze();
 151                 if (kthread_should_stop())
 152                         break;
 153
 154                 mutex_lock(&dev->mutex);
 155                 cur_jiffies = jiffies;
 156                 if (dev->sdr_cap_seq_resync) {
 157                         dev->jiffies_sdr_cap = cur_jiffies;
 158                         dev->sdr_cap_seq_offset = dev->sdr_cap_seq_count + 1;
 159                         dev->sdr_cap_seq_count = 0;
 160                         dev->sdr_cap_seq_resync = false;
 161                 }
 162                 /* Calculate the number of jiffies since we started streaming */
 163                 jiffies_since_start = cur_jiffies - dev->jiffies_sdr_cap;
 164                 /* Get the number of buffers streamed since the start */
 165                 buffers_since_start = (u64)jiffies_since_start * dev->sdr_adc_freq +
 166                                       (HZ * SDR_CAP_SAMPLES_PER_BUF) / 2;
 167                 do_div(buffers_since_start, HZ * SDR_CAP_SAMPLES_PER_BUF);
 168
 169                 /*
 170                  * After more than 0xf0000000 (rounded down to a multiple of
 171                  * 'jiffies-per-day' to ease jiffies_to_msecs calculation)
 172                  * jiffies have passed since we started streaming reset the
 173                  * counters and keep track of the sequence offset.
 174                  */
 175                 if (jiffies_since_start > JIFFIES_RESYNC) {
 176                         dev->jiffies_sdr_cap = cur_jiffies;
 177                         dev->sdr_cap_seq_offset = buffers_since_start;
 178                         buffers_since_start = 0;
 179                 }
 180                 dev->sdr_cap_seq_count = buffers_since_start + dev->sdr_cap_seq_offset;
 181
 182                 vivid_thread_sdr_cap_tick(dev);
 183                 mutex_unlock(&dev->mutex);
 184
 185                 /*
 186                  * Calculate the number of samples streamed since we started,
 187                  * not including the current buffer.
 188                  */
 189                 samples_since_start = buffers_since_start * SDR_CAP_SAMPLES_PER_BUF;
 190
 191                 /* And the number of jiffies since we started */
 192                 jiffies_since_start = jiffies - dev->jiffies_sdr_cap;
 193
 194                 /* Increase by the number of samples in one buffer */
 195                 samples_since_start += SDR_CAP_SAMPLES_PER_BUF;
 196                 /*
 197                  * Calculate when that next buffer is supposed to start
 198                  * in jiffies since we started streaming.
 199                  */
 200                 next_jiffies_since_start = samples_since_start * HZ +
 201                                            dev->sdr_adc_freq / 2;
 202                 do_div(next_jiffies_since_start, dev->sdr_adc_freq);
 203                 /* If it is in the past, then just schedule asap */
 204                 if (next_jiffies_since_start < jiffies_since_start)
 205                         next_jiffies_since_start = jiffies_since_start;
 206
 207                 wait_jiffies = next_jiffies_since_start - jiffies_since_start;
 208                 schedule_timeout_interruptible(wait_jiffies ? wait_jiffies : 1);
 209         }
 210         dprintk(dev, 1, "SDR Capture Thread End\n");
 211         return 0;
 212 }
 213
 214 static int sdr_cap_queue_setup(struct vb2_queue *vq, const struct v4l2_format *fmt,
 215                        unsigned *nbuffers, unsigned *nplanes,
 216                        unsigned sizes[], void *alloc_ctxs[])
 217 {
 218         /* 2 = max 16-bit sample returned */
 219         sizes[0] = SDR_CAP_SAMPLES_PER_BUF * 2;
 220         *nplanes = 1;
 221         return 0;
 222 }
 223
 224 static int sdr_cap_buf_prepare(struct vb2_buffer *vb)
 225 {
 226         struct vivid_dev *dev = vb2_get_drv_priv(vb->vb2_queue);
 227         unsigned size = SDR_CAP_SAMPLES_PER_BUF * 2;
 228
 229         dprintk(dev, 1, "%s\n", __func__);
 230
 231         if (dev->buf_prepare_error) {
 232                 /*
 233                  * Error injection: test what happens if buf_prepare() returns
 234                  * an error.
 235                  */
 236                 dev->buf_prepare_error = false;
 237                 return -EINVAL;
 238         }
 239         if (vb2_plane_size(vb, 0) < size) {
 240                 dprintk(dev, 1, "%s data will not fit into plane (%lu < %u)\n",
 241                                 __func__, vb2_plane_size(vb, 0), size);
 242                 return -EINVAL;
 243         }
 244         vb2_set_plane_payload(vb, 0, size);
 245
 246         return 0;
 247 }
 248
 249 static void sdr_cap_buf_queue(struct vb2_buffer *vb)
 250 {
 251         struct vivid_dev *dev = vb2_get_drv_priv(vb->vb2_queue);
 252         struct vivid_buffer *buf = container_of(vb, struct vivid_buffer, vb);
 253
 254         dprintk(dev, 1, "%s\n", __func__);
 255
 256         spin_lock(&dev->slock);
 257         list_add_tail(&buf->list, &dev->sdr_cap_active);
 258         spin_unlock(&dev->slock);
 259 }
 260
 261 static int sdr_cap_start_streaming(struct vb2_queue *vq, unsigned count)
 262 {
 263         struct vivid_dev *dev = vb2_get_drv_priv(vq);
 264         int err = 0;
 265
 266         dprintk(dev, 1, "%s\n", __func__);
 267         dev->sdr_cap_seq_count = 0;
 268         if (dev->start_streaming_error) {
 269                 dev->start_streaming_error = false;
 270                 err = -EINVAL;
 271         } else if (dev->kthread_sdr_cap == NULL) {
 272                 dev->kthread_sdr_cap = kthread_run(vivid_thread_sdr_cap, dev,
 273                                 "%s-sdr-cap", dev->v4l2_dev.name);
 274
 275                 if (IS_ERR(dev->kthread_sdr_cap)) {
 276                         v4l2_err(&dev->v4l2_dev, "kernel_thread() failed\n");
 277                         err = PTR_ERR(dev->kthread_sdr_cap);
 278                         dev->kthread_sdr_cap = NULL;
 279                 }
 280         }
 281         if (err) {
 282                 struct vivid_buffer *buf, *tmp;
 283
 284                 list_for_each_entry_safe(buf, tmp, &dev->sdr_cap_active, list) {
 285                         list_del(&buf->list);
 286                         vb2_buffer_done(&buf->vb, VB2_BUF_STATE_QUEUED);
 287                 }
 288         }
 289         return err;
 290 }
 291
 292 /* abort streaming and wait for last buffer */
 293 static void sdr_cap_stop_streaming(struct vb2_queue *vq)
 294 {
 295         struct vivid_dev *dev = vb2_get_drv_priv(vq);
 296
 297         if (dev->kthread_sdr_cap == NULL)
 298                 return;
 299
 300         while (!list_empty(&dev->sdr_cap_active)) {
 301                 struct vivid_buffer *buf;
 302
 303                 buf = list_entry(dev->sdr_cap_active.next, struct vivid_buffer, list);
 304                 list_del(&buf->list);
 305                 vb2_buffer_done(&buf->vb, VB2_BUF_STATE_ERROR);
 306         }
 307
 308         /* shutdown control thread */
 309         mutex_unlock(&dev->mutex);
 310         kthread_stop(dev->kthread_sdr_cap);
 311         dev->kthread_sdr_cap = NULL;
 312         mutex_lock(&dev->mutex);
 313 }
 314
 315 const struct vb2_ops vivid_sdr_cap_qops = {
 316         .queue_setup            = sdr_cap_queue_setup,
 317         .buf_prepare            = sdr_cap_buf_prepare,
 318         .buf_queue              = sdr_cap_buf_queue,
 319         .start_streaming        = sdr_cap_start_streaming,
 320         .stop_streaming         = sdr_cap_stop_streaming,
 321         .wait_prepare           = vb2_ops_wait_prepare,
 322         .wait_finish            = vb2_ops_wait_finish,
 323 };
 324
 325 int vivid_sdr_enum_freq_bands(struct file *file, void *fh, struct v4l2_frequency_band *band)
 326 {
 327         switch (band->tuner) {
 328         case 0:
 329                 if (band->index >= ARRAY_SIZE(bands_adc))
 330                         return -EINVAL;
 331                 *band = bands_adc[band->index];
 332                 return 0;
 333         case 1:
 334                 if (band->index >= ARRAY_SIZE(bands_fm))
 335                         return -EINVAL;
 336                 *band = bands_fm[band->index];
 337                 return 0;
 338         default:
 339                 return -EINVAL;
 340         }
 341 }
 342
 343 int vivid_sdr_g_frequency(struct file *file, void *fh, struct v4l2_frequency *vf)
 344 {
 345         struct vivid_dev *dev = video_drvdata(file);
 346
 347         switch (vf->tuner) {
 348         case 0:
 349                 vf->frequency = dev->sdr_adc_freq;
 350                 vf->type = V4L2_TUNER_ADC;
 351                 return 0;
 352         case 1:
 353                 vf->frequency = dev->sdr_fm_freq;
 354                 vf->type = V4L2_TUNER_RF;
 355                 return 0;
 356         default:
 357                 return -EINVAL;
 358         }
 359 }
 360
 361 int vivid_sdr_s_frequency(struct file *file, void *fh, const struct v4l2_frequency *vf)
 362 {
 363         struct vivid_dev *dev = video_drvdata(file);
 364         unsigned freq = vf->frequency;
 365         unsigned band;
 366
 367         switch (vf->tuner) {
 368         case 0:
 369                 if (vf->type != V4L2_TUNER_ADC)
 370                         return -EINVAL;
 371                 if (freq < BAND_ADC_0)
 372                         band = 0;
 373                 else if (freq < BAND_ADC_1)
 374                         band = 1;
 375                 else
 376                         band = 2;
 377
 378                 freq = clamp_t(unsigned, freq,
 379                                 bands_adc[band].rangelow,
 380                                 bands_adc[band].rangehigh);
 381
 382                 if (vb2_is_streaming(&dev->vb_sdr_cap_q) &&
 383                     freq != dev->sdr_adc_freq) {
 384                         /* resync the thread's timings */
 385                         dev->sdr_cap_seq_resync = true;
 386                 }
 387                 dev->sdr_adc_freq = freq;
 388                 return 0;
 389         case 1:
 390                 if (vf->type != V4L2_TUNER_RF)
 391                         return -EINVAL;
 392                 dev->sdr_fm_freq = clamp_t(unsigned, freq,
 393                                 bands_fm[0].rangelow,
 394                                 bands_fm[0].rangehigh);
 395                 return 0;
 396         default:
 397                 return -EINVAL;
 398         }
 399 }
 400
 401 int vivid_sdr_g_tuner(struct file *file, void *fh, struct v4l2_tuner *vt)
 402 {
 403         switch (vt->index) {
 404         case 0:
 405                 strlcpy(vt->name, "ADC", sizeof(vt->name));
 406                 vt->type = V4L2_TUNER_ADC;
 407                 vt->capability = V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS;
 408                 vt->rangelow = bands_adc[0].rangelow;
 409                 vt->rangehigh = bands_adc[2].rangehigh;
 410                 return 0;
 411         case 1:
 412                 strlcpy(vt->name, "RF", sizeof(vt->name));
 413                 vt->type = V4L2_TUNER_RF;
 414                 vt->capability = V4L2_TUNER_CAP_1HZ | V4L2_TUNER_CAP_FREQ_BANDS;
 415                 vt->rangelow = bands_fm[0].rangelow;
 416                 vt->rangehigh = bands_fm[0].rangehigh;
 417                 return 0;
 418         default:
 419                 return -EINVAL;
 420         }
 421 }
 422
 423 int vivid_sdr_s_tuner(struct file *file, void *fh, const struct v4l2_tuner *vt)
 424 {
 425         if (vt->index > 1)
 426                 return -EINVAL;
 427         return 0;
 428 }
 429
 430 int vidioc_enum_fmt_sdr_cap(struct file *file, void *fh, struct v4l2_fmtdesc *f)
 431 {
 432         if (f->index >= ARRAY_SIZE(formats))
 433                 return -EINVAL;
 434         f->pixelformat = formats[f->index].pixelformat;
 435         return 0;
 436 }
 437
 438 int vidioc_g_fmt_sdr_cap(struct file *file, void *fh, struct v4l2_format *f)
 439 {
 440         struct vivid_dev *dev = video_drvdata(file);
 441
 442         f->fmt.sdr.pixelformat = dev->sdr_pixelformat;
 443         f->fmt.sdr.buffersize = dev->sdr_buffersize;
 444         memset(f->fmt.sdr.reserved, 0, sizeof(f->fmt.sdr.reserved));
 445         return 0;
 446 }
 447
 448 int vidioc_s_fmt_sdr_cap(struct file *file, void *fh, struct v4l2_format *f)
 449 {
 450         struct vivid_dev *dev = video_drvdata(file);
 451         struct vb2_queue *q = &dev->vb_sdr_cap_q;
 452         int i;
 453
 454         if (vb2_is_busy(q))
 455                 return -EBUSY;
 456
 457         memset(f->fmt.sdr.reserved, 0, sizeof(f->fmt.sdr.reserved));
 458         for (i = 0; i < ARRAY_SIZE(formats); i++) {
 459                 if (formats[i].pixelformat == f->fmt.sdr.pixelformat) {
 460                         dev->sdr_pixelformat = formats[i].pixelformat;
 461                         dev->sdr_buffersize = formats[i].buffersize;
 462                         f->fmt.sdr.buffersize = formats[i].buffersize;
 463                         return 0;
 464                 }
 465         }
 466         dev->sdr_pixelformat = formats[0].pixelformat;
 467         dev->sdr_buffersize = formats[0].buffersize;
 468         f->fmt.sdr.pixelformat = formats[0].pixelformat;
 469         f->fmt.sdr.buffersize = formats[0].buffersize;
 470         return 0;
 471 }
 472
 473 int vidioc_try_fmt_sdr_cap(struct file *file, void *fh, struct v4l2_format *f)
 474 {
 475         int i;
 476
 477         memset(f->fmt.sdr.reserved, 0, sizeof(f->fmt.sdr.reserved));
 478         for (i = 0; i < ARRAY_SIZE(formats); i++) {
 479                 if (formats[i].pixelformat == f->fmt.sdr.pixelformat) {
 480                         f->fmt.sdr.buffersize = formats[i].buffersize;
 481                         return 0;
 482                 }
 483         }
 484         f->fmt.sdr.pixelformat = formats[0].pixelformat;
 485         f->fmt.sdr.buffersize = formats[0].buffersize;
 486         return 0;
 487 }
 488
 489 #define FIXP_N    (15)
 490 #define FIXP_FRAC (1 << FIXP_N)
 491 #define FIXP_2PI  ((int)(2 * 3.141592653589 * FIXP_FRAC))
 492 #define M_100000PI (3.14159 * 100000)
 493
 494 void vivid_sdr_cap_process(struct vivid_dev *dev, struct vivid_buffer *buf)
 495 {
 496         u8 *vbuf = vb2_plane_vaddr(&buf->vb, 0);
 497         unsigned long i;
 498         unsigned long plane_size = vb2_plane_size(&buf->vb, 0);
 499         s64 s64tmp;
 500         s32 src_phase_step;
 501         s32 mod_phase_step;
 502         s32 fixp_i;
 503         s32 fixp_q;
 504
 505         /* calculate phase step */
 506         #define BEEP_FREQ 1000 /* 1kHz beep */
 507         src_phase_step = DIV_ROUND_CLOSEST(FIXP_2PI * BEEP_FREQ,
 508                                            dev->sdr_adc_freq);
 509
 510         for (i = 0; i < plane_size; i += 2) {
 511                 mod_phase_step = fixp_cos32_rad(dev->sdr_fixp_src_phase,
 512                                                 FIXP_2PI) >> (31 - FIXP_N);
 513
 514                 dev->sdr_fixp_src_phase += src_phase_step;
 515                 s64tmp = (s64) mod_phase_step * dev->sdr_fm_deviation;
 516                 dev->sdr_fixp_mod_phase += div_s64(s64tmp, M_100000PI);
 517
 518                 /*
 519                  * Transfer phase angle to [0, 2xPI] in order to avoid variable
 520                  * overflow and make it suitable for cosine implementation
 521                  * used, which does not support negative angles.
 522                  */
 523                 dev->sdr_fixp_src_phase %= FIXP_2PI;
 524                 dev->sdr_fixp_mod_phase %= FIXP_2PI;
 525
 526                 if (dev->sdr_fixp_mod_phase < 0)
 527                         dev->sdr_fixp_mod_phase += FIXP_2PI;
 528
 529                 fixp_i = fixp_cos32_rad(dev->sdr_fixp_mod_phase, FIXP_2PI);
 530                 fixp_q = fixp_sin32_rad(dev->sdr_fixp_mod_phase, FIXP_2PI);
 531
 532                 /* Normalize fraction values represented with 32 bit precision
 533                  * to fixed point representation with FIXP_N bits */
 534                 fixp_i >>= (31 - FIXP_N);
 535                 fixp_q >>= (31 - FIXP_N);
 536
 537                 switch (dev->sdr_pixelformat) {
 538                 case V4L2_SDR_FMT_CU8:
 539                         /* convert 'fixp float' to u8 [0, +255] */
 540                         /* u8 = X * 127.5 + 127.5; X is float [-1.0, +1.0] */
 541                         fixp_i = fixp_i * 1275 + FIXP_FRAC * 1275;
 542                         fixp_q = fixp_q * 1275 + FIXP_FRAC * 1275;
 543                         *vbuf++ = DIV_ROUND_CLOSEST(fixp_i, FIXP_FRAC * 10);
 544                         *vbuf++ = DIV_ROUND_CLOSEST(fixp_q, FIXP_FRAC * 10);
 545                         break;
 546                 case V4L2_SDR_FMT_CS8:
 547                         /* convert 'fixp float' to s8 [-128, +127] */
 548                         /* s8 = X * 127.5 - 0.5; X is float [-1.0, +1.0] */
 549                         fixp_i = fixp_i * 1275 - FIXP_FRAC * 5;
 550                         fixp_q = fixp_q * 1275 - FIXP_FRAC * 5;
 551                         *vbuf++ = DIV_ROUND_CLOSEST(fixp_i, FIXP_FRAC * 10);
 552                         *vbuf++ = DIV_ROUND_CLOSEST(fixp_q, FIXP_FRAC * 10);
 553                         break;
 554                 default:
 555                         break;
 556                 }
 557         }
 558 }