1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
|
/*
* 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 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;
int good_bits;
int failed = 0;
if (!buffer[0]) {
buffer[0] = ao_usb_alloc();
buffer[1] = ao_usb_alloc();
if (!buffer[0])
return;
}
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 (;;) {
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);
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");
}
|
