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ll/rand: restructure rand initialization #970

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771bbfa
ll/rand: restructure rand initialization
haukepetersen Apr 14, 2021
76a24bd
fixup! fix scope for PRNG seeding
haukepetersen Apr 15, 2021
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1 change: 0 additions & 1 deletion nimble/controller/include/controller/ble_ll.h
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Original file line number Diff line number Diff line change
Expand Up @@ -581,7 +581,6 @@ int ble_ll_rand_init(void);
void ble_ll_rand_sample(uint8_t rnum);
int ble_ll_rand_data_get(uint8_t *buf, uint8_t len);
void ble_ll_rand_prand_get(uint8_t *prand);
int ble_ll_rand_start(void);
uint32_t ble_ll_rand(void);

static inline int
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2 changes: 0 additions & 2 deletions nimble/controller/src/ble_ll.c
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Expand Up @@ -1687,8 +1687,6 @@ ble_ll_init(void)

/* Initialize random number generation */
ble_ll_rand_init();
/* Start the random number generator */
ble_ll_rand_start();

rc = stats_init_and_reg(STATS_HDR(ble_ll_stats),
STATS_SIZE_INIT_PARMS(ble_ll_stats, STATS_SIZE_32),
Expand Down
42 changes: 15 additions & 27 deletions nimble/controller/src/ble_ll_rand.c
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Expand Up @@ -47,6 +47,8 @@ struct ble_ll_rnum_data
struct ble_ll_rnum_data g_ble_ll_rnum_data;
uint8_t g_ble_ll_rnum_buf[MYNEWT_VAL(BLE_LL_RNG_BUFSIZE)];

static unsigned short xsubi[3];

#define IS_RNUM_BUF_END(x) \
(x == &g_ble_ll_rnum_buf[MYNEWT_VAL(BLE_LL_RNG_BUFSIZE) - 1])

Expand Down Expand Up @@ -127,14 +129,6 @@ ble_ll_rand_data_get(uint8_t *buf, uint8_t len)
uint32_t
ble_ll_rand(void)
{
static unsigned short xsubi[3];
static bool init = true;

if (init) {
init = false;
ble_ll_rand_data_get((uint8_t *)xsubi, sizeof(xsubi));
}

return (uint32_t) jrand48(xsubi);
}

Expand Down Expand Up @@ -164,25 +158,6 @@ ble_ll_rand_prand_get(uint8_t *prand)
prand[2] |= 0x40;
}

/**
* Start the generation of random numbers
*
* @return int
*/
int
ble_ll_rand_start(void)
{
#if MYNEWT_VAL(TRNG)
/* Nothing to do - this is handled by driver */
#else
/* Start the generation of numbers if we are not full */
if (g_ble_ll_rnum_data.rnd_size < MYNEWT_VAL(BLE_LL_RNG_BUFSIZE)) {
ble_hw_rng_start();
}
#endif
return 0;
}

/**
* Initialize LL random number generation. Should be called only once on
* initialization.
Expand All @@ -198,6 +173,19 @@ ble_ll_rand_init(void)
g_ble_ll_rnum_data.rnd_in = g_ble_ll_rnum_buf;
g_ble_ll_rnum_data.rnd_out = g_ble_ll_rnum_buf;
ble_hw_rng_init(ble_ll_rand_sample, 1);

/* Start the generation of numbers if we are not full */
if (g_ble_ll_rnum_data.rnd_size < MYNEWT_VAL(BLE_LL_RNG_BUFSIZE)) {
ble_hw_rng_start();
}
#endif

/* Seed the pseudo random number generator (jrand48) */
ble_ll_rand_data_get((uint8_t *)xsubi, sizeof(xsubi));
/* We need to trigger jrand48 once discarding its output, as the initial
* call to jrand48 causes dynamic memory allocation by the libc. We do not
* want this to happen in interrupt context, which can happen if we wait for
* the first actual call to ble_ll_rand(). */
ble_ll_rand();
return 0;
}