native: Add basic ble_hw_rng implementation

nimble/drivers/native/src/ble_hw.c

@@ -20,6 +20,8 @@
 #include <stdint.h>
 #include <assert.h>
 #include <string.h>
+#include <stdlib.h>
+#include <stdbool.h>
 #include "syscfg/syscfg.h"
 #include "os/os.h"
 #include "nimble/ble.h"
@@ -32,6 +34,9 @@
 /* We use this to keep track of which entries are set to valid addresses */
 static uint8_t g_ble_hw_whitelist_mask;
 
+static ble_rng_isr_cb_t rng_cb;
+static bool rng_started;
+
 /* Returns public device address or -1 if not present */
 int
 ble_hw_get_public_addr(ble_addr_t *addr)
@@ -143,7 +148,8 @@ ble_hw_encrypt_block(struct ble_encryption_block *ecb)
 int
 ble_hw_rng_init(ble_rng_isr_cb_t cb, int bias)
 {
-    return -1;
+    rng_cb = cb;
+    return 0;
 }
 
 /**
@@ -154,7 +160,15 @@ ble_hw_rng_init(ble_rng_isr_cb_t cb, int bias)
 int
 ble_hw_rng_start(void)
 {
-    return -1;
+    rng_started = true;
+
+    if (rng_cb) {
+        while (rng_started) {
+            rng_cb(rand());
+        }
+    }
+
+    return 0;
 }
 
 /**
@@ -165,7 +179,8 @@ ble_hw_rng_start(void)
 int
 ble_hw_rng_stop(void)
 {
-    return -1;
+    rng_started = false;
+    return 0;
 }
 
 /**
@@ -176,7 +191,7 @@ ble_hw_rng_stop(void)
 uint8_t
 ble_hw_rng_read(void)
 {
-    return 0;
+    return rand();
 }
 
 #if MYNEWT_VAL(BLE_LL_CFG_FEAT_LL_PRIVACY)