Make SC16Q11-nodc conversions table-based for speed.

Add a mechanism for converters to initialize tables on demand.
Move UC8 table setup to the new lazy-setup path.
Fix uc8 lookup table allocation size.
This commit is contained in:
Oliver Jowett 2017-01-27 21:58:12 +00:00
parent 8a41bcb730
commit 417cda7061
4 changed files with 252 additions and 88 deletions

243
convert.c
View file

@ -26,6 +26,36 @@ struct converter_state {
float z1_Q;
};
static uint16_t *uc8_lookup;
static bool init_uc8_lookup()
{
if (uc8_lookup)
return true;
uc8_lookup = malloc(sizeof(uint16_t) * 256 * 256);
if (!uc8_lookup) {
fprintf(stderr, "can't allocate UC8 conversion lookup table\n");
return false;
}
for (int i = 0; i <= 255; i++) {
for (int q = 0; q <= 255; q++) {
float fI, fQ, magsq;
fI = (i - 127.5) / 127.5;
fQ = (q - 127.5) / 127.5;
magsq = fI * fI + fQ * fQ;
if (magsq > 1)
magsq = 1;
float mag = sqrtf(magsq);
uc8_lookup[le16toh((i*256)+q)] = (uint16_t) (mag * 65535.0f + 0.5f);
}
}
return true;
}
static void convert_uc8_nodc(void *iq_data,
uint16_t *mag_data,
unsigned nsamples,
@ -42,55 +72,33 @@ static void convert_uc8_nodc(void *iq_data,
MODES_NOTUSED(state);
// unroll this a bit
#define DO_ONE_SAMPLE \
do { \
mag = uc8_lookup[*in++]; \
*mag_data++ = mag; \
sum_level += mag; \
sum_power += (uint32_t)mag * (uint32_t)mag; \
} while(0)
// unroll this a bit
for (i = 0; i < (nsamples>>3); ++i) {
mag = Modes.maglut[*in++];
*mag_data++ = mag;
sum_level += mag;
sum_power += (uint32_t)mag * (uint32_t)mag;
mag = Modes.maglut[*in++];
*mag_data++ = mag;
sum_level += mag;
sum_power += (uint32_t)mag * (uint32_t)mag;
mag = Modes.maglut[*in++];
*mag_data++ = mag;
sum_level += mag;
sum_power += (uint32_t)mag * (uint32_t)mag;
mag = Modes.maglut[*in++];
*mag_data++ = mag;
sum_level += mag;
sum_power += (uint32_t)mag * (uint32_t)mag;
mag = Modes.maglut[*in++];
*mag_data++ = mag;
sum_level += mag;
sum_power += (uint32_t)mag * (uint32_t)mag;
mag = Modes.maglut[*in++];
*mag_data++ = mag;
sum_level += mag;
sum_power += (uint32_t)mag * (uint32_t)mag;
mag = Modes.maglut[*in++];
*mag_data++ = mag;
sum_level += mag;
sum_power += (uint32_t)mag * (uint32_t)mag;
mag = Modes.maglut[*in++];
*mag_data++ = mag;
sum_level += mag;
sum_power += (uint32_t)mag * (uint32_t)mag;
DO_ONE_SAMPLE;
DO_ONE_SAMPLE;
DO_ONE_SAMPLE;
DO_ONE_SAMPLE;
DO_ONE_SAMPLE;
DO_ONE_SAMPLE;
DO_ONE_SAMPLE;
DO_ONE_SAMPLE;
}
for (i = 0; i < (nsamples&7); ++i) {
mag = Modes.maglut[*in++];
*mag_data++ = mag;
sum_level += mag;
sum_power += (uint32_t)mag * (uint32_t)mag;
DO_ONE_SAMPLE;
}
#undef DO_ONE_SAMPLE
if (out_mean_level) {
*out_mean_level = sum_level / 65536.0 / nsamples;
}
@ -204,6 +212,125 @@ static void convert_sc16_generic(void *iq_data,
}
}
static void convert_sc16_nodc(void *iq_data,
uint16_t *mag_data,
unsigned nsamples,
struct converter_state *state,
double *out_mean_level,
double *out_mean_power)
{
MODES_NOTUSED(state);
uint16_t *in = iq_data;
unsigned i;
int16_t I, Q;
float fI, fQ, magsq;
float sum_level = 0, sum_power = 0;
for (i = 0; i < nsamples; ++i) {
I = (int16_t)le16toh(*in++);
Q = (int16_t)le16toh(*in++);
fI = I / 32768.0f;
fQ = Q / 32768.0f;
magsq = fI * fI + fQ * fQ;
if (magsq > 1)
magsq = 1;
float mag = sqrtf(magsq);
sum_power += magsq;
sum_level += mag;
*mag_data++ = (uint16_t)(mag * 65535.0f + 0.5f);
}
if (out_mean_level) {
*out_mean_level = sum_level / nsamples;
}
if (out_mean_power) {
*out_mean_power = sum_power / nsamples;
}
}
// SC16Q11_TABLE_BITS controls the size of the lookup table
// for SC16Q11 data. The size of the table is 2 * (1 << (2*BITS))
// bytes. Reducing the number of bits reduces precision but
// can run substantially faster by staying in cache.
// See convert_benchmark.c for some numbers.
// Leaving SC16QQ_TABLE_BITS undefined will disable the table lookup and always use
// the floating-point path, which may be faster on some systems
#if defined(SC16Q11_TABLE_BITS)
#define USE_BITS SC16Q11_TABLE_BITS
#define LOSE_BITS (11 - SC16Q11_TABLE_BITS)
static uint16_t *sc16q11_lookup;
static bool init_sc16q11_lookup()
{
if (sc16q11_lookup)
return true;
sc16q11_lookup = malloc(sizeof(uint16_t) * (1 << (USE_BITS * 2)));
if (!sc16q11_lookup) {
fprintf(stderr, "can't allocate SC16Q11 conversion lookup table\n");
return false;
}
for (int i = 0; i < 2048; i += (1 << LOSE_BITS)) {
for (int q = 0; q < 2048; q += (1 << LOSE_BITS)) {
float fI = i / 2048.0, fQ = q / 2048.0;
float magsq = fI * fI + fQ * fQ;
if (magsq > 1)
magsq = 1;
float mag = sqrtf(magsq);
unsigned index = ((i >> LOSE_BITS) << USE_BITS) | (q >> LOSE_BITS);
sc16q11_lookup[index] = (uint16_t)(mag * 65535.0f + 0.5f);
}
}
return true;
}
static void convert_sc16q11_table(void *iq_data,
uint16_t *mag_data,
unsigned nsamples,
struct converter_state *state,
double *out_mean_level,
double *out_mean_power)
{
uint16_t *in = iq_data;
unsigned i;
uint16_t I, Q;
uint64_t sum_level = 0;
uint64_t sum_power = 0;
uint16_t mag;
MODES_NOTUSED(state);
for (i = 0; i < nsamples; ++i) {
I = abs((int16_t)le16toh(*in++)) & 2047;
Q = abs((int16_t)le16toh(*in++)) & 2047;
mag = sc16q11_lookup[((I >> LOSE_BITS) << USE_BITS) | (Q >> LOSE_BITS)];
*mag_data++ = mag;
sum_level += mag;
sum_power += (uint32_t)mag * (uint32_t)mag;
}
if (out_mean_level) {
*out_mean_level = sum_level / 65536.0 / nsamples;
}
if (out_mean_power) {
*out_mean_power = sum_power / 65535.0 / 65535.0 / nsamples;
}
}
#else /* ! defined(SC16Q11_TABLE_BITS) */
static void convert_sc16q11_nodc(void *iq_data,
uint16_t *mag_data,
unsigned nsamples,
@ -211,14 +338,15 @@ static void convert_sc16q11_nodc(void *iq_data,
double *out_mean_level,
double *out_mean_power)
{
MODES_NOTUSED(state);
uint16_t *in = iq_data;
unsigned i;
int16_t I, Q;
float fI, fQ, magsq;
float sum_level = 0, sum_power = 0;
MODES_NOTUSED(state);
for (i = 0; i < nsamples; ++i) {
I = (int16_t)le16toh(*in++);
Q = (int16_t)le16toh(*in++);
@ -244,6 +372,8 @@ static void convert_sc16q11_nodc(void *iq_data,
}
}
#endif /* defined(SC16Q11_TABLE_BITS) */
static void convert_sc16q11_generic(void *iq_data,
uint16_t *mag_data,
unsigned nsamples,
@ -301,14 +431,20 @@ static struct {
int can_filter_dc;
iq_convert_fn fn;
const char *description;
bool (*init)();
} converters_table[] = {
// In order of preference
{ INPUT_UC8, 0, convert_uc8_nodc, "UC8, integer/table path" },
{ INPUT_UC8, 1, convert_uc8_generic, "UC8, float path" },
{ INPUT_SC16, 1, convert_sc16_generic, "SC16, float path" },
{ INPUT_SC16Q11, 0, convert_sc16q11_nodc, "SC16Q11, float path, no DC block" },
{ INPUT_SC16Q11, 1, convert_sc16q11_generic, "SC16Q11, float path" },
{ 0, 0, NULL, NULL }
{ INPUT_UC8, 0, convert_uc8_nodc, "UC8, integer/table path", init_uc8_lookup },
{ INPUT_UC8, 1, convert_uc8_generic, "UC8, float path", NULL },
{ INPUT_SC16, 0, convert_sc16_nodc, "SC16, float path, no DC", NULL },
{ INPUT_SC16, 1, convert_sc16_generic, "SC16, float path", NULL },
#if defined(SC16Q11_TABLE_BITS)
{ INPUT_SC16Q11, 0, convert_sc16q11_table, "SC16Q11, integer/table path", init_sc16q11_lookup },
#else
{ INPUT_SC16Q11, 0, convert_sc16q11_nodc, "SC16Q11, float path, no DC", NULL },
#endif
{ INPUT_SC16Q11, 1, convert_sc16q11_generic, "SC16Q11, float path", NULL },
{ 0, 0, NULL, NULL, NULL }
};
iq_convert_fn init_converter(input_format_t format,
@ -332,6 +468,11 @@ iq_convert_fn init_converter(input_format_t format,
return NULL;
}
if (converters_table[i].init) {
if (!converters_table[i].init())
return NULL;
}
*out_state = malloc(sizeof(struct converter_state));
if (! *out_state) {
fprintf(stderr, "can't allocate converter state\n");

View file

@ -1,35 +1,75 @@
#include "dump1090.h"
static uint8_t *testdata_uc8;
static uint16_t *testdata_sc16;
static uint16_t *testdata_sc16q11;
static void **testdata_uc8;
static void **testdata_sc16;
static void **testdata_sc16q11;
static uint16_t *outdata;
// SC16Q11_TABLE_BITS notes:
// 11 bits (8MB) gives you full precision, but a large table that doesn't fit in cache
// 9 bits (512kB) will fit in the Pi 2/3's shared L2 cache
// (but there will be contention from other cores)
// 8 bits (128kB) will fit in the Pi 1's L2 cache
// 7 bits (32kB) will fit in the Pi 1/2/3's L1 cache
// Sample results for "SC16Q11, no DC":
// Core i7-3610QM @ 2300MHz
// SC16Q11_TABLE_BITS undefined: 152.80M samples/second
// SC16Q11_TABLE_BITS=11: 101.22M samples/second
// SC16Q11_TABLE_BITS=9: 243.04M samples/second
// SC16Q11_TABLE_BITS=8: 316.84M samples/second
// SC16Q11_TABLE_BITS=7: 375.70M samples/second
// Pi3B @ 1200MHz
// SC16Q11_TABLE_BITS undefined: 22.19M samples/second
// SC16Q11_TABLE_BITS=11: 5.86M samples/second
// SC16Q11_TABLE_BITS=9: 19.33M samples/second
// SC16Q11_TABLE_BITS=8: 33.50M samples/second
// SC16Q11_TABLE_BITS=7: 59.78M samples/second
// Pi1B @ 700MHz
// SC16Q11_TABLE_BITS undefined: 5.24M samples/second
// SC16Q11_TABLE_BITS=11: 2.53M samples/second
// SC16Q11_TABLE_BITS=9: 3.23M samples/second
// SC16Q11_TABLE_BITS=8: 5.77M samples/second
// SC16Q11_TABLE_BITS=7: 10.23M samples/second
void prepare()
{
srand(1);
testdata_uc8 = calloc(MODES_MAG_BUF_SAMPLES, 2);
testdata_sc16 = calloc(MODES_MAG_BUF_SAMPLES, 4);
testdata_sc16q11 = calloc(MODES_MAG_BUF_SAMPLES, 4);
testdata_uc8 = calloc(10, sizeof(void*));
testdata_sc16 = calloc(10, sizeof(void*));
testdata_sc16q11 = calloc(10, sizeof(void*));
outdata = calloc(MODES_MAG_BUF_SAMPLES, sizeof(uint16_t));
for (unsigned i = 0; i < MODES_MAG_BUF_SAMPLES; ++i) {
double I = 2.0 * rand() / (RAND_MAX + 1.0) - 1.0;
double Q = 2.0 * rand() / (RAND_MAX + 1.0) - 1.0;
for (int buf = 0; buf < 10; ++buf) {
uint8_t *uc8 = calloc(MODES_MAG_BUF_SAMPLES, 2);
testdata_uc8[buf] = uc8;;
uint16_t *sc16 = calloc(MODES_MAG_BUF_SAMPLES, 4);
testdata_sc16[buf] = sc16;
uint16_t *sc16q11 = calloc(MODES_MAG_BUF_SAMPLES, 4);
testdata_sc16q11[buf] = sc16q11;
testdata_uc8[i*2] = (uint8_t) (I * 128 + 128);
testdata_uc8[i*2+1] = (uint8_t) (Q * 128 + 128);
for (unsigned i = 0; i < MODES_MAG_BUF_SAMPLES; ++i) {
double I = 2.0 * rand() / (RAND_MAX + 1.0) - 1.0;
double Q = 2.0 * rand() / (RAND_MAX + 1.0) - 1.0;
testdata_sc16[i*2] = htole16( (int16_t) (I * 32768.0) );
testdata_sc16[i*2+1] = htole16( (int16_t) (Q * 32768.0) );
uc8[i*2] = (uint8_t) (I * 128 + 128);
uc8[i*2+1] = (uint8_t) (Q * 128 + 128);
testdata_sc16q11[i*2] = htole16( (int16_t) (I * 2048.0) );
testdata_sc16q11[i*2+1] = htole16( (int16_t) (Q * 2048.0) );
sc16[i*2] = htole16( (int16_t) (I * 32768.0) );
sc16[i*2+1] = htole16( (int16_t) (Q * 32768.0) );
sc16q11[i*2] = htole16( (int16_t) (I * 2048.0) );
sc16q11[i*2+1] = htole16( (int16_t) (Q * 2048.0) );
}
}
}
void test(const char *what, input_format_t format, void *data, double sample_rate, bool filter_dc) {
void test(const char *what, input_format_t format, void **data, double sample_rate, bool filter_dc) {
fprintf(stderr, "Benchmarking: %s ", what);
struct converter_state *state;
@ -43,7 +83,7 @@ void test(const char *what, input_format_t format, void *data, double sample_rat
int iterations = 0;
// Run it once to force init.
converter(data, outdata, MODES_MAG_BUF_SAMPLES, state, NULL, NULL);
converter(data[0], outdata, MODES_MAG_BUF_SAMPLES, state, NULL, NULL);
while (total.tv_sec < 5) {
fprintf(stderr, ".");
@ -52,7 +92,7 @@ void test(const char *what, input_format_t format, void *data, double sample_rat
start_cpu_timing(&start);
for (int i = 0; i < 10; ++i) {
converter(data, outdata, MODES_MAG_BUF_SAMPLES, state, NULL, NULL);
converter(data[i], outdata, MODES_MAG_BUF_SAMPLES, state, NULL, NULL);
}
end_cpu_timing(&start, &total);

View file

@ -129,7 +129,7 @@ void modesInitConfig(void) {
//=========================================================================
//
void modesInit(void) {
int i, q;
int i;
pthread_mutex_init(&Modes.data_mutex,NULL);
pthread_cond_init(&Modes.data_cond,NULL);
@ -139,8 +139,7 @@ void modesInit(void) {
// Allocate the various buffers used by Modes
Modes.trailing_samples = (MODES_PREAMBLE_US + MODES_LONG_MSG_BITS + 16) * 1e-6 * Modes.sample_rate;
if ( ((Modes.maglut = (uint16_t *) malloc(sizeof(uint16_t) * 256 * 256) ) == NULL) ||
((Modes.log10lut = (uint16_t *) malloc(sizeof(uint16_t) * 256 * 256) ) == NULL) )
if ( ((Modes.log10lut = (uint16_t *) malloc(sizeof(uint16_t) * 256 * 256) ) == NULL) )
{
fprintf(stderr, "Out of memory allocating data buffer.\n");
exit(1);
@ -184,21 +183,6 @@ void modesInit(void) {
if (Modes.net_sndbuf_size > (MODES_NET_SNDBUF_MAX))
{Modes.net_sndbuf_size = MODES_NET_SNDBUF_MAX;}
// compute UC8 magnitude lookup table
for (i = 0; i <= 255; i++) {
for (q = 0; q <= 255; q++) {
float fI, fQ, magsq;
fI = (i - 127.5) / 127.5;
fQ = (q - 127.5) / 127.5;
magsq = fI * fI + fQ * fQ;
if (magsq > 1)
magsq = 1;
Modes.maglut[le16toh((i*256)+q)] = (uint16_t) round(sqrtf(magsq) * 65535.0);
}
}
// Prepare the log10 lookup table: 100log10(x)
Modes.log10lut[0] = 0; // poorly defined..
for (i = 1; i <= 65535; i++) {

View file

@ -276,7 +276,6 @@ struct { // Internal state
unsigned trailing_samples; // extra trailing samples in magnitude buffers
double sample_rate; // actual sample rate in use (in hz)
uint16_t *maglut; // I/Q -> Magnitude lookup table
uint16_t *log10lut; // Magnitude -> log10 lookup table
int exit; // Exit from the main loop when true