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   1 /*
   2  * Copyright © 2014 Keith Packard <keithp@keithp.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; version 2 of the License.
   7  *
   8  * This program is distributed in the hope that it will be useful, but
   9  * WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  16  */
  17
  18 #include <ao.h>
  19 #include <ao_adc_fast.h>
  20
  21 static const uint16_t crc16_table[256] = {
  22         0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241,
  23         0xC601, 0x06C0, 0x0780, 0xC741, 0x0500, 0xC5C1, 0xC481, 0x0440,
  24         0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40,
  25         0x0A00, 0xCAC1, 0xCB81, 0x0B40, 0xC901, 0x09C0, 0x0880, 0xC841,
  26         0xD801, 0x18C0, 0x1980, 0xD941, 0x1B00, 0xDBC1, 0xDA81, 0x1A40,
  27         0x1E00, 0xDEC1, 0xDF81, 0x1F40, 0xDD01, 0x1DC0, 0x1C80, 0xDC41,
  28         0x1400, 0xD4C1, 0xD581, 0x1540, 0xD701, 0x17C0, 0x1680, 0xD641,
  29         0xD201, 0x12C0, 0x1380, 0xD341, 0x1100, 0xD1C1, 0xD081, 0x1040,
  30         0xF001, 0x30C0, 0x3180, 0xF141, 0x3300, 0xF3C1, 0xF281, 0x3240,
  31         0x3600, 0xF6C1, 0xF781, 0x3740, 0xF501, 0x35C0, 0x3480, 0xF441,
  32         0x3C00, 0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0, 0x3E80, 0xFE41,
  33         0xFA01, 0x3AC0, 0x3B80, 0xFB41, 0x3900, 0xF9C1, 0xF881, 0x3840,
  34         0x2800, 0xE8C1, 0xE981, 0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41,
  35         0xEE01, 0x2EC0, 0x2F80, 0xEF41, 0x2D00, 0xEDC1, 0xEC81, 0x2C40,
  36         0xE401, 0x24C0, 0x2580, 0xE541, 0x2700, 0xE7C1, 0xE681, 0x2640,
  37         0x2200, 0xE2C1, 0xE381, 0x2340, 0xE101, 0x21C0, 0x2080, 0xE041,
  38         0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281, 0x6240,
  39         0x6600, 0xA6C1, 0xA781, 0x6740, 0xA501, 0x65C0, 0x6480, 0xA441,
  40         0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80, 0xAE41,
  41         0xAA01, 0x6AC0, 0x6B80, 0xAB41, 0x6900, 0xA9C1, 0xA881, 0x6840,
  42         0x7800, 0xB8C1, 0xB981, 0x7940, 0xBB01, 0x7BC0, 0x7A80, 0xBA41,
  43         0xBE01, 0x7EC0, 0x7F80, 0xBF41, 0x7D00, 0xBDC1, 0xBC81, 0x7C40,
  44         0xB401, 0x74C0, 0x7580, 0xB541, 0x7700, 0xB7C1, 0xB681, 0x7640,
  45         0x7200, 0xB2C1, 0xB381, 0x7340, 0xB101, 0x71C0, 0x7080, 0xB041,
  46         0x5000, 0x90C1, 0x9181, 0x5140, 0x9301, 0x53C0, 0x5280, 0x9241,
  47         0x9601, 0x56C0, 0x5780, 0x9741, 0x5500, 0x95C1, 0x9481, 0x5440,
  48         0x9C01, 0x5CC0, 0x5D80, 0x9D41, 0x5F00, 0x9FC1, 0x9E81, 0x5E40,
  49         0x5A00, 0x9AC1, 0x9B81, 0x5B40, 0x9901, 0x59C0, 0x5880, 0x9841,
  50         0x8801, 0x48C0, 0x4980, 0x8941, 0x4B00, 0x8BC1, 0x8A81, 0x4A40,
  51         0x4E00, 0x8EC1, 0x8F81, 0x4F40, 0x8D01, 0x4DC0, 0x4C80, 0x8C41,
  52         0x4400, 0x84C1, 0x8581, 0x4540, 0x8701, 0x47C0, 0x4680, 0x8641,
  53         0x8201, 0x42C0, 0x4380, 0x8341, 0x4100, 0x81C1, 0x8081, 0x4040,
  54 };
  55
  56 static void
  57 ao_trng_fetch(void)
  58 {
  59         static uint16_t *buffer[2];
  60         static uint16_t adc_in[AO_USB_IN_SIZE]; /* twice as many as we need */
  61         uint32_t        kbytes = 1;
  62         uint32_t        count;
  63         int             usb_buf_id;
  64         int             i, j;
  65         uint16_t        crc16 = 0;
  66         uint16_t        *buf;
  67         uint8_t         *rnd;
  68
  69         if (!buffer[0]) {
  70                 buffer[0] = ao_usb_alloc();
  71                 buffer[1] = ao_usb_alloc();
  72                 if (!buffer[0])
  73                         return;
  74         }
  75
  76         ao_cmd_decimal();
  77         if (ao_cmd_status == ao_cmd_success)
  78                 kbytes = ao_cmd_lex_u32;
  79         else
  80                 ao_cmd_status = ao_cmd_success;
  81         usb_buf_id = 0;
  82         count = kbytes * (1024/AO_USB_IN_SIZE);
  83         ao_led_on(AO_LED_GREEN);
  84         while (count--) {
  85                 ao_adc_read(adc_in, AO_USB_IN_SIZE);
  86                 rnd = (uint8_t *) adc_in;
  87                 buf = buffer[usb_buf_id];
  88                 for (i = 0; i < 32; i++) {
  89                         for (j = 0; j < 4; j++)
  90                                 crc16 = (crc16 >> 8) ^ crc16_table[(crc16 ^ *rnd++) & 0xff];
  91                         *buf++ = crc16;
  92                 }
  93                 ao_led_toggle(AO_LED_GREEN|AO_LED_RED);
  94                 ao_usb_write(buffer[usb_buf_id], AO_USB_IN_SIZE);
  95                 ao_led_toggle(AO_LED_GREEN|AO_LED_RED);
  96                 usb_buf_id = 1-usb_buf_id;
  97         }
  98         ao_led_off(AO_LED_GREEN|AO_LED_RED);
  99         ao_usb_flush();
 100 }
 101
 102 static const struct ao_cmds usbtrng_cmds[] = {
 103         { ao_trng_fetch,        "f\0Fetch a block of numbers" },
 104         { 0, NULL },
 105 };
 106
 107 void main(void)
 108 {
 109         ao_led_init(LEDS_AVAILABLE);
 110         ao_led_on(AO_LED_RED);
 111         ao_clock_init();
 112         ao_task_init();
 113         ao_timer_init();
 114         ao_dma_init();
 115         ao_adc_init();
 116
 117         ao_cmd_init();
 118
 119         ao_usb_init();
 120
 121         ao_cmd_register(usbtrng_cmds);
 122         ao_led_off(AO_LED_RED);
 123
 124         ao_start_scheduler();
 125 }