Optimize decimation performance
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parent
2811d56298
commit
15f559d816
95
src/main.c
95
src/main.c
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@ -24,7 +24,7 @@
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#define VREG_VOLTAGE VREG_VOLTAGE_1_20
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#define CLK_SYS_HZ (288 * MHZ)
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#define INIT_SAMPLE_RATE 100000
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#define INIT_SAMPLE_RATE 200000
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#define INIT_FREQ 94600000
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#define INIT_GAIN 127
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@ -64,20 +64,19 @@ static uint32_t nco_addr = (uint32_t)lo_phase;
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#define DECIMATE 16
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#define RX_BITS_DEPTH 8
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#define RX_WORDS (1 << (RX_BITS_DEPTH - 2))
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#define RX_STRIDE (2 * DECIMATE)
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static_assert(RX_WORDS >= 4 * DECIMATE, "RX_WORDS >= 4 * DECIMATE");
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static_assert(RX_WORDS >= 2 * RX_STRIDE, "RX_WORDS >= 2 * RX_STRIDE");
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static uint32_t rx_cos[RX_WORDS] __attribute__((__aligned__(1 << RX_BITS_DEPTH)));
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static const uint32_t *rx_start = rx_cos;
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static const uint32_t *rx_end = rx_cos + RX_WORDS - 1;
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#define NUM_GAINS 29
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static int gains[NUM_GAINS] = { 0, 9, 14, 27, 37, 77, 87, 125, 144, 157,
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166, 197, 207, 229, 254, 280, 297, 328, 338, 364,
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372, 386, 402, 421, 434, 439, 445, 480, 496 };
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static int sample_rate = INIT_SAMPLE_RATE;
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static int dc_level = CLK_SYS_HZ / INIT_SAMPLE_RATE / 2;
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static int max_amplitude = CLK_SYS_HZ / INIT_SAMPLE_RATE / 2;
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static int max_amplitude_mul = 65536 / (CLK_SYS_HZ / INIT_SAMPLE_RATE / 2);
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static int gain = INIT_GAIN;
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static int frequency = INIT_FREQ;
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@ -456,97 +455,116 @@ struct IQ {
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int I, Q;
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};
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inline static int get_next_sample()
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inline static const uint32_t *next_stride()
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{
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static const uint32_t *tail = rx_cos;
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static int tail = 0;
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const uint32_t *head = (const uint32_t *)dma_hw->ch[dma_ch_in_cos].write_addr;
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int head, delta;
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while (head == tail) {
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asm volatile("nop; nop; nop; nop");
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head = (const uint32_t *)dma_hw->ch[dma_ch_in_cos].write_addr;
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}
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loop:
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head = (dma_hw->ch[dma_ch_in_cos].write_addr >> 2) & (RX_WORDS - 1);
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delta = head - tail;
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int value = -(*tail++);
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value *= 2;
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value -= *tail++;
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if (delta < 0)
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delta += RX_WORDS;
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if (tail > rx_end)
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tail = rx_start;
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if (delta < RX_STRIDE)
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goto loop;
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return gain * value - dc_level;
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const uint32_t *stride = rx_cos + tail;
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tail = (tail + RX_STRIDE) & (RX_WORDS - 1);
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return stride;
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}
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inline static int nextQ(const uint32_t **stride)
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{
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int x2 = *(*stride)++;
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int x1 = *(*stride)++;
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return (x2 << 1) + x1 + max_amplitude;
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}
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inline static struct IQ next_sample()
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{
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int I = 0, Q = 0;
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int x15 = get_next_sample();
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const uint32_t *stride = next_stride();
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int x15 = nextQ(&stride);
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I += 93 * x15;
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Q += 39 * x15;
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int x14 = get_next_sample();
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int x14 = nextQ(&stride);
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I += 71 * x14;
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Q += 71 * x14;
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int x13 = get_next_sample();
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int x13 = nextQ(&stride);
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I += 39 * x13;
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Q += 93 * x13;
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int x12 = get_next_sample();
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int x12 = nextQ(&stride);
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I += 0 * x12;
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Q += 101 * x12;
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int x11 = get_next_sample();
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int x11 = nextQ(&stride);
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I += -39 * x11;
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Q += 93 * x11;
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int x10 = get_next_sample();
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int x10 = nextQ(&stride);
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I += -71 * x10;
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Q += 71 * x10;
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int x09 = get_next_sample();
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int x09 = nextQ(&stride);
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I += -93 * x09;
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Q += 39 * x09;
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int x08 = get_next_sample();
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int x08 = nextQ(&stride);
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I += -101 * x08;
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Q += 0 * x08;
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int x07 = get_next_sample();
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int x07 = nextQ(&stride);
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I += -93 * x07;
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Q += -39 * x07;
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int x06 = get_next_sample();
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int x06 = nextQ(&stride);
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I += -71 * x06;
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Q += -71 * x06;
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int x05 = get_next_sample();
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int x05 = nextQ(&stride);
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I += -39 * x05;
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Q += -93 * x05;
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int x04 = get_next_sample();
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int x04 = nextQ(&stride);
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I += 0 * x04;
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Q += -101 * x04;
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int x03 = get_next_sample();
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int x03 = nextQ(&stride);
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I += 39 * x03;
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Q += -93 * x03;
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int x02 = get_next_sample();
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int x02 = nextQ(&stride);
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I += 71 * x02;
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Q += -71 * x02;
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int x01 = get_next_sample();
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int x01 = nextQ(&stride);
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I += 93 * x01;
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Q += -39 * x01;
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int x00 = get_next_sample();
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int x00 = nextQ(&stride);
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I += 101 * x00;
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Q += 0 * x00;
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I *= gain;
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I /= 1024;
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I *= max_amplitude_mul;
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I /= (1 << 16);
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Q *= gain;
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Q /= 1024;
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Q *= max_amplitude_mul;
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Q /= (1 << 16);
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return (struct IQ){ I, Q };
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}
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@ -568,8 +586,6 @@ static void rf_rx(void)
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int64_t I = IQ.I;
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int64_t Q = IQ.Q;
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I /= dc_level;
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if (I > 127)
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I = 127;
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else if (I < -128)
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@ -577,8 +593,6 @@ static void rf_rx(void)
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*blockptr++ = (uint8_t)I + 128;
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Q /= dc_level;
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if (Q > 127)
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Q = 127;
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else if (Q < -128)
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@ -602,7 +616,8 @@ static void run_command(uint8_t cmd, uint32_t arg)
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} else if (0x02 == cmd) {
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/* Set the rate at which IQ sample pairs are sent */
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sample_rate = arg;
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dc_level = CLK_SYS_HZ / sample_rate / 2;
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max_amplitude = CLK_SYS_HZ / sample_rate / 2;
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max_amplitude_mul = 65536 / max_amplitude;
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dma_timer_set_fraction(dma_t_samp, 1, CLK_SYS_HZ / (sample_rate * DECIMATE));
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rx_lo_init(frequency + sample_rate);
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} else if (0x04 == cmd) {
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