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/*
* Copyright © 2015 Keith Packard <keithp@keithp.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
*/
#include <ao.h>
#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 void
ao_trng_send_raw(uint16_t *buf)
{
uint16_t i;
uint16_t t;
uint16_t *rnd = (uint16_t *) ao_adc_ring;
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++) {
*buf++ = rnd[t];
t = (t + 1) & (AO_ADC_RING_SIZE - 1);
}
}
static void
ao_trng_send_cooked(uint16_t *buf)
{
uint16_t i;
uint16_t t;
uint32_t *rnd = (uint32_t *) ao_adc_ring;
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++) {
*buf++ = ao_crc_in_32_out_16(rnd[t]);
t = (t + 1) & ((AO_ADC_RING_SIZE>>1) - 1);
}
}
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;
if (!buffer[0]) {
buffer[0] = ao_usb_alloc();
buffer[1] = ao_usb_alloc();
if (!buffer[0])
return;
}
usb_buf_id = 0;
ao_crc_reset();
for (;;) {
if (!trng_running) {
/* Delay long enough for the HV power supply
* to stabilize so that the first bits we read
* aren't of poor quality
*/
ao_delay(AO_MS_TO_TICKS(10));
trng_running = TRUE;
}
if (ao_send_raw()) {
ao_led_on(AO_LED_TRNG_RAW);
ao_trng_send_raw(buffer[usb_buf_id]);
ao_led_off(AO_LED_TRNG_RAW);
} else {
ao_led_on(AO_LED_TRNG_COOKED);
ao_trng_send_cooked(buffer[usb_buf_id]);
ao_led_off(AO_LED_TRNG_COOKED);
}
ao_adc_ack(AO_USB_IN_SIZE);
ao_usb_write(buffer[usb_buf_id], AO_USB_IN_SIZE);
usb_buf_id = 1-usb_buf_id;
}
}
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
}
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, 1);
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");
}
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