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Small enhancement: it is not necessary to output two different bits.

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Signed-off-by: Pol Henarejos <pol.henarejos@cttc.es>
This commit is contained in:
Pol Henarejos
2022-08-22 00:04:16 +02:00
parent 23604e8549
commit b10999d52f
1 changed files with 7 additions and 6 deletions
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13
firmware/pico_rng.c
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@@ -243,7 +243,7 @@ void usb_start_transfer(struct usb_endpoint_configuration *ep, uint8_t *buf, uin
// For multi packet transfers see the tinyusb port.
assert(len <= 64);
printf("Start transfer of len %d on ep addr 0x%x\n", len, ep->descriptor->bEndpointAddress);
//printf("Start transfer of len %d on ep addr 0x%x\n", len, ep->descriptor->bEndpointAddress);
// Prepare buffer control register value
uint32_t val = len | USB_BUF_CTRL_AVAIL;
@@ -450,7 +450,7 @@ static void usb_handle_ep_buff_done(struct usb_endpoint_configuration *ep) {
*/
static void usb_handle_buff_done(uint ep_num, bool in) {
uint8_t ep_addr = ep_num | (in ? USB_DIR_IN : 0);
printf("EP %d (in = %d) done\n", ep_num, in);
//printf("EP %d (in = %d) done\n", ep_num, in);
for (uint i = 0; i < USB_NUM_ENDPOINTS; i++) {
struct usb_endpoint_configuration *ep = &dev_config.endpoints[i];
if (ep->descriptor && ep->handler) {
@@ -559,15 +559,16 @@ void ep0_out_handler(uint8_t *buf, uint16_t len) {
* @param len the length of the random data in bytes
*/
void get_random_data(char *buf, uint16_t len) {
uint64_t word = 0x0;
if (len > 64)
len = 64;
memset(buf, 0, len);
/* This algorithm generates 2 words, i.e., 8 bytes. */
for (int i = 0; i < len; i += 8) {
/* We apply Fowler–Noll–Vo hash function as it randomizes the input and is quite fast. */
for (int i = 0; i < len; i += sizeof(uint64_t)) {
uint64_t random_word = 0xcbf29ce484222325;
for (int round = 0; round < 8; round++)
{
uint64_t word = 0x0;
for (int n = 0; n < 64; n++)
{
uint8_t bit1, bit2;
@@ -576,7 +577,7 @@ void get_random_data(char *buf, uint16_t len) {
bit1 = rosc_hw->randombit & 0xff;
// sleep_ms(1);
bit2 = rosc_hw->randombit & 0xff;
} while (bit1 == bit2);
} while (0);
word = (word << 1) | bit1;
}
random_word ^= word^board_millis()^adc_read();
@@ -595,7 +596,7 @@ void get_random_data(char *buf, uint16_t len) {
*/
void ep1_in_handler(uint8_t *buf, uint16_t len) {
printf("Sent %d bytes to host\n", len);
//printf("Sent %d bytes to host\n", len);
// Prime the EP1 IN buffer for the next transfer
get_random_data(ep1_buf, 64);