/*
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* Licensed to the Apache Software Foundation (ASF) under one
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* or more contributor license agreements. See the NOTICE file
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* distributed with this work for additional information
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* regarding copyright ownership. The ASF licenses this file
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* to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing,
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* software distributed under the License is distributed on an
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* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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* KIND, either express or implied. See the License for the
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* specific language governing permissions and limitations
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* under the License.
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*/
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#include <assert.h>
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#include <stdlib.h>
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#include "nimble/ble.h"
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#include "controller/ble_ll.h"
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#include "controller/ble_ll_tmr.h"
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#include "controller/ble_ll_utils.h"
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/* 37 bits require 5 bytes */
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#define BLE_LL_CHMAP_LEN (5)
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/* Sleep clock accuracy table (in ppm) */
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static const uint16_t g_ble_sca_ppm_tbl[8] = {
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500, 250, 150, 100, 75, 50, 30, 20
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};
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uint32_t
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ble_ll_utils_calc_access_addr(void)
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{
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uint32_t aa;
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uint16_t aa_low;
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uint16_t aa_high;
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uint32_t temp;
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uint32_t mask;
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uint32_t prev_bit;
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uint8_t bits_diff;
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uint8_t consecutive;
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uint8_t transitions;
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uint8_t ones;
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int tmp;
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/* Calculate a random access address */
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aa = 0;
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while (1) {
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/* Get two, 16-bit random numbers */
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aa_low = ble_ll_rand() & 0xFFFF;
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aa_high = ble_ll_rand() & 0xFFFF;
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/* All four bytes cannot be equal */
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if (aa_low == aa_high) {
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continue;
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}
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/* Upper 6 bits must have 2 transitions */
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tmp = (int16_t)aa_high >> 10;
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if (__builtin_popcount(tmp ^ (tmp >> 1)) < 2) {
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continue;
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}
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/* Cannot be access address or be 1 bit different */
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aa = aa_high;
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aa = (aa << 16) | aa_low;
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bits_diff = 0;
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temp = aa ^ BLE_ACCESS_ADDR_ADV;
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for (mask = 0x00000001; mask != 0; mask <<= 1) {
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if (mask & temp) {
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++bits_diff;
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if (bits_diff > 1) {
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break;
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}
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}
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}
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if (bits_diff <= 1) {
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continue;
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}
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/* Cannot have more than 24 transitions */
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transitions = 0;
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consecutive = 1;
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ones = 0;
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mask = 0x00000001;
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while (mask < 0x80000000) {
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prev_bit = aa & mask;
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mask <<= 1;
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if (mask & aa) {
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if (prev_bit == 0) {
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++transitions;
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consecutive = 1;
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} else {
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++consecutive;
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}
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} else {
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if (prev_bit == 0) {
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++consecutive;
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} else {
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++transitions;
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consecutive = 1;
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}
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}
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if (prev_bit) {
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ones++;
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}
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/* 8 lsb should have at least three 1 */
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if (mask == 0x00000100 && ones < 3) {
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break;
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}
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/* 16 lsb should have no more than 11 transitions */
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if (mask == 0x00010000 && transitions > 11) {
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break;
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}
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/* This is invalid! */
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if (consecutive > 6) {
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/* Make sure we always detect invalid sequence below */
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mask = 0;
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break;
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}
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}
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/* Invalid sequence found */
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if (mask != 0x80000000) {
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continue;
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}
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/* Cannot be more than 24 transitions */
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if (transitions > 24) {
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continue;
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}
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/* We have a valid access address */
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break;
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}
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return aa;
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}
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uint8_t
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ble_ll_utils_remapped_channel(uint8_t remap_index, const uint8_t *chanmap)
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{
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uint8_t cntr;
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uint8_t mask;
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uint8_t usable_chans;
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uint8_t chan;
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int i, j;
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/* NOTE: possible to build a map but this would use memory. For now,
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* we just calculate
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* Iterate through channel map to find this channel
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*/
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chan = 0;
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cntr = 0;
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for (i = 0; i < BLE_LL_CHMAP_LEN; i++) {
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usable_chans = chanmap[i];
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if (usable_chans != 0) {
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mask = 0x01;
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for (j = 0; j < 8; j++) {
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if (usable_chans & mask) {
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if (cntr == remap_index) {
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return (chan + j);
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}
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++cntr;
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}
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mask <<= 1;
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}
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}
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chan += 8;
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}
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/* we should never reach here */
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BLE_LL_ASSERT(0);
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return 0;
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}
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uint8_t
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ble_ll_utils_calc_num_used_chans(const uint8_t *chan_map)
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{
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uint32_t u32 = 0;
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uint32_t num_used_chans = 0;
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unsigned idx;
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for (idx = 0; idx < 37; idx++) {
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if ((idx % 8) == 0) {
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u32 = chan_map[idx / 8];
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}
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if (u32 & 1) {
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num_used_chans++;
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}
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u32 >>= 1;
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}
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return num_used_chans;
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}
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#if MYNEWT_VAL(BLE_LL_CFG_FEAT_LE_CSA2)
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#if __thumb2__
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static inline uint32_t
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ble_ll_utils_csa2_perm(uint32_t val)
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{
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__asm__ volatile (".syntax unified \n"
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"rbit %[val], %[val] \n"
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"rev %[val], %[val] \n"
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: [val] "+r" (val));
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return val;
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}
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#else
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static uint32_t
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ble_ll_utils_csa2_perm(uint32_t in)
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{
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uint32_t out = 0;
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int i;
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for (i = 0; i < 8; i++) {
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out |= ((in >> i) & 0x00000001) << (7 - i);
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}
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for (i = 8; i < 16; i++) {
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out |= ((in >> i) & 0x00000001) << (15 + 8 - i);
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}
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return out;
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}
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#endif
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static inline uint32_t
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ble_ll_utils_csa2_mam(uint32_t a, uint32_t b)
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{
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return (17 * a + b) % 65536;
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}
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static uint16_t
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ble_ll_utils_csa2_prn_s(uint16_t counter, uint16_t ch_id)
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{
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uint32_t prn_s;
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prn_s = counter ^ ch_id;
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prn_s = ble_ll_utils_csa2_perm(prn_s);
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prn_s = ble_ll_utils_csa2_mam(prn_s, ch_id);
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prn_s = ble_ll_utils_csa2_perm(prn_s);
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prn_s = ble_ll_utils_csa2_mam(prn_s, ch_id);
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prn_s = ble_ll_utils_csa2_perm(prn_s);
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prn_s = ble_ll_utils_csa2_mam(prn_s, ch_id);
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return prn_s;
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}
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static uint16_t
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ble_ll_utils_csa2_prng(uint16_t counter, uint16_t ch_id)
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{
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uint16_t prn_s;
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uint16_t prn_e;
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prn_s = ble_ll_utils_csa2_prn_s(counter, ch_id);
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prn_e = prn_s ^ ch_id;
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return prn_e;
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}
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/* Find remap_idx for given chan_idx */
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static uint16_t
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ble_ll_utils_csa2_chan2remap(uint16_t chan_idx, const uint8_t *chan_map)
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{
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uint16_t remap_idx = 0;
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uint32_t u32 = 0;
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unsigned idx;
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for (idx = 0; idx < 37; idx++) {
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if ((idx % 8) == 0) {
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u32 = chan_map[idx / 8];
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}
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if (u32 & 1) {
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if (idx == chan_idx) {
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return remap_idx;
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}
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remap_idx++;
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}
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u32 >>= 1;
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}
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BLE_LL_ASSERT(0);
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return 0;
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}
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/* Find chan_idx at given remap_idx */
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static uint16_t
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ble_ll_utils_csa2_remap2chan(uint16_t remap_idx, const uint8_t *chan_map)
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{
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uint32_t u32 = 0;
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unsigned idx;
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for (idx = 0; idx < 37; idx++) {
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if ((idx % 8) == 0) {
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u32 = chan_map[idx / 8];
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}
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if (u32 & 1) {
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if (!remap_idx) {
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return idx;
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}
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remap_idx--;
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}
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u32 >>= 1;
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}
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BLE_LL_ASSERT(0);
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return 0;
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}
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static uint16_t
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ble_ll_utils_csa2_calc_chan_idx(uint16_t prn_e, uint8_t num_used_chans,
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const uint8_t *chanm_map, uint16_t *remap_idx)
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{
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uint16_t chan_idx;
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chan_idx = prn_e % 37;
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if (chanm_map[chan_idx / 8] & (1 << (chan_idx % 8))) {
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*remap_idx = ble_ll_utils_csa2_chan2remap(chan_idx, chanm_map);
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return chan_idx;
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}
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*remap_idx = (num_used_chans * prn_e) / 65536;
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chan_idx = ble_ll_utils_csa2_remap2chan(*remap_idx, chanm_map);
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return chan_idx;
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}
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uint8_t
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ble_ll_utils_dci_csa2(uint16_t counter, uint16_t chan_id,
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uint8_t num_used_chans, const uint8_t *chan_map)
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{
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uint16_t prn_e;
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uint16_t chan_idx;
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uint16_t remap_idx;
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prn_e = ble_ll_utils_csa2_prng(counter, chan_id);
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chan_idx = ble_ll_utils_csa2_calc_chan_idx(prn_e, num_used_chans, chan_map,
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&remap_idx);
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return chan_idx;
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}
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uint16_t
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ble_ll_utils_dci_iso_event(uint16_t counter, uint16_t chan_id,
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uint16_t *prn_sub_lu, uint8_t num_used_chans,
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const uint8_t *chan_map, uint16_t *remap_idx)
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{
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uint16_t prn_s;
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uint16_t prn_e;
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uint16_t chan_idx;
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prn_s = ble_ll_utils_csa2_prn_s(counter, chan_id);
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prn_e = prn_s ^ chan_id;
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*prn_sub_lu = prn_s;
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chan_idx = ble_ll_utils_csa2_calc_chan_idx(prn_e, num_used_chans, chan_map,
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remap_idx);
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return chan_idx;
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}
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uint16_t
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ble_ll_utils_dci_iso_subevent(uint16_t chan_id, uint16_t *prn_sub_lu,
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uint8_t num_used_chans, const uint8_t *chan_map,
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uint16_t *remap_idx)
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{
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uint16_t prn_sub_se;
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uint16_t chan_idx;
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uint16_t d;
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*prn_sub_lu = ble_ll_utils_csa2_perm(*prn_sub_lu);
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*prn_sub_lu = ble_ll_utils_csa2_mam(*prn_sub_lu, chan_id);
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prn_sub_se = *prn_sub_lu ^ chan_id;
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/* Core 5.3, Vol 6, Part B, 4.5.8.3.6 (enjoy!) */
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/* TODO optimize this somehow */
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d = max(1, max(min(3, num_used_chans - 5),
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min(11, (num_used_chans - 10) / 2)));
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*remap_idx = (*remap_idx + d + prn_sub_se *
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(num_used_chans - 2 * d + 1) / 65536) % num_used_chans;
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chan_idx = ble_ll_utils_csa2_remap2chan(*remap_idx, chan_map);
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return chan_idx;
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}
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#endif
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uint32_t
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ble_ll_utils_calc_window_widening(uint32_t anchor_point,
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uint32_t last_anchor_point,
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uint8_t central_sca)
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{
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uint32_t total_sca_ppm;
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uint32_t window_widening;
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int32_t time_since_last_anchor;
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uint32_t delta_msec;
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window_widening = 0;
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time_since_last_anchor = (int32_t)(anchor_point - last_anchor_point);
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if (time_since_last_anchor > 0) {
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delta_msec = ble_ll_tmr_t2u(time_since_last_anchor) / 1000;
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total_sca_ppm = g_ble_sca_ppm_tbl[central_sca] + MYNEWT_VAL(BLE_LL_SCA);
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window_widening = (total_sca_ppm * delta_msec) / 1000;
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}
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return window_widening;
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}
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