#include <ao_adc_fast.h>
#include <ao_crc.h>
#include <ao_trng_send.h>
+#include <ao_exti.h>
+#include <ao_power.h>
+
+static uint8_t trng_running;
+static AO_TICK_TYPE trng_power_time;
+
+/* Make sure there's at least 8 bits of variance in the samples */
+#define MIN_VARIANCE (128 * 128)
+
+#define DECLARE_STATS int32_t sum = 0, sum2 = 0
+
+#define ADD_STATS(value) do { \
+ sum += (value); \
+ sum2 += (value) * (value); \
+ } while(0)
+
+#define GOOD_STATS(i) (((sum2 - (sum * sum) / i) / i) >= MIN_VARIANCE)
+
+#define TRNG_ENABLE_DELAY AO_MS_TO_TICKS(100)
+
+static int
+ao_trng_send_raw(uint16_t *buf)
+{
+ uint16_t i;
+ uint16_t t;
+ uint16_t v;
+
+ DECLARE_STATS;
+
+ t = ao_adc_get(AO_USB_IN_SIZE>>1); /* one 16-bit value per two output bytes */
+ for (i = 0; i < AO_USB_IN_SIZE / sizeof (uint16_t); i++) {
+ v = ao_adc_ring[t];
+ *buf++ = v;
+ t = (t + 1) & (AO_ADC_RING_SIZE - 1);
+
+ ADD_STATS(v);
+ }
+ return GOOD_STATS(AO_USB_IN_SIZE / sizeof (uint16_t));
+}
+
+static int
+ao_trng_send_cooked(uint16_t *buf)
+{
+ uint16_t i;
+ uint16_t t;
+ uint32_t *rnd = (uint32_t *) ao_adc_ring;
+
+ DECLARE_STATS;
+
+ t = ao_adc_get(AO_USB_IN_SIZE) >> 1; /* one 16-bit value per output byte */
+
+ for (i = 0; i < AO_USB_IN_SIZE / sizeof (uint16_t); i++) {
+ uint32_t v;
+ uint16_t v1, v2;
+
+ /* Fetch two values in one operation */
+ v = rnd[t];
+ t = (t + 1) & ((AO_ADC_RING_SIZE >> 1) - 1);
+
+ *buf++ = ao_crc_in_32_out_16(v);
+
+ v1 = v;
+ v2 = v >> 16;
+
+ ADD_STATS(v1);
+ ADD_STATS(v2);
+ }
+ return GOOD_STATS(2 * AO_USB_IN_SIZE / sizeof (uint16_t));
+}
+
+static inline int
+ao_send_raw(void)
+{
+ return !ao_gpio_get(AO_RAW_PORT, AO_RAW_BIT, AO_RAW_PIN);
+}
static void
ao_trng_send(void)
{
static uint16_t *buffer[2];
- int usb_buf_id;
- uint16_t i;
- uint16_t *buf;
- uint32_t *rnd;
+ int usb_buf_id;
+ int good_bits;
+ int failed = 0;
if (!buffer[0]) {
buffer[0] = ao_usb_alloc();
usb_buf_id = 0;
+#ifdef AO_TRNG_ENABLE_PORT
+ ao_gpio_set(AO_TRNG_ENABLE_PORT, AO_TRNG_ENABLE_BIT, AO_TRNG_ENABLE_PIN, 1);
+#endif
+ trng_power_time = ao_time();
+
ao_crc_reset();
for (;;) {
- ao_led_on(AO_LED_TRNG_ACTIVE);
- rnd = (uint32_t *) ao_adc_get(AO_USB_IN_SIZE); /* one 16-bit value per output byte */
- buf = buffer[usb_buf_id];
- for (i = 0; i < AO_USB_IN_SIZE / sizeof (uint16_t); i++)
- *buf++ = ao_crc_in_32_out_16(*rnd++);
+ if (!trng_running) {
+ AO_TICK_TYPE delay;
+
+ delay = trng_power_time + TRNG_ENABLE_DELAY - ao_time();
+ if (delay > TRNG_ENABLE_DELAY)
+ delay = TRNG_ENABLE_DELAY;
+
+ /* Delay long enough for the HV power supply
+ * to stabilize so that the first bits we read
+ * aren't of poor quality
+ */
+ ao_delay(delay);
+ trng_running = TRUE;
+ }
+ if (ao_send_raw()) {
+ ao_led_on(AO_LED_TRNG_RAW);
+ good_bits = ao_trng_send_raw(buffer[usb_buf_id]);
+ ao_led_off(AO_LED_TRNG_RAW);
+ } else {
+ ao_led_on(AO_LED_TRNG_COOKED);
+ good_bits = ao_trng_send_cooked(buffer[usb_buf_id]);
+ ao_led_off(AO_LED_TRNG_COOKED);
+ }
ao_adc_ack(AO_USB_IN_SIZE);
- ao_led_off(AO_LED_TRNG_ACTIVE);
- ao_usb_write(buffer[usb_buf_id], AO_USB_IN_SIZE);
- usb_buf_id = 1-usb_buf_id;
+ if (good_bits) {
+ ao_usb_write(buffer[usb_buf_id], AO_USB_IN_SIZE);
+ usb_buf_id = 1-usb_buf_id;
+ failed = 0;
+ } else {
+ failed++;
+ ao_delay(AO_MS_TO_TICKS(10));
+ if (failed > 10) {
+ ao_usb_disable();
+ ao_panic(AO_PANIC_DMA);
+ }
+ }
}
}
static struct ao_task ao_trng_send_task;
+#if AO_POWER_MANAGEMENT
+
+static void ao_trng_suspend(void *arg)
+{
+ (void) arg;
+#ifdef AO_TRNG_ENABLE_PORT
+ ao_gpio_set(AO_TRNG_ENABLE_PORT, AO_TRNG_ENABLE_BIT, AO_TRNG_ENABLE_PIN, 0);
+#endif
+ trng_running = FALSE;
+}
+
+static void ao_trng_resume(void *arg)
+{
+ (void) arg;
+#ifdef AO_TRNG_ENABLE_PORT
+ ao_gpio_set(AO_TRNG_ENABLE_PORT, AO_TRNG_ENABLE_BIT, AO_TRNG_ENABLE_PIN, 1);
+#endif
+ trng_power_time = ao_time();
+}
+
+static struct ao_power ao_trng_power = {
+ .suspend = ao_trng_suspend,
+ .resume = ao_trng_resume
+};
+
+#endif
+
void
ao_trng_send_init(void)
{
+#ifdef AO_TRNG_ENABLE_PORT
+ ao_enable_output(AO_TRNG_ENABLE_PORT, AO_TRNG_ENABLE_BIT, AO_TRNG_ENABLE_PIN, 0);
+ ao_power_register(&ao_trng_power);
+#endif
+ ao_enable_input(AO_RAW_PORT, AO_RAW_BIT, AO_EXTI_MODE_PULL_UP);
ao_add_task(&ao_trng_send_task, ao_trng_send, "trng_send");
}
projects / fw / altos / blobdiff