[mynewt-nimble] 01/03: nimble/ll: Optimize num used channels calculation

[an...@apache.org]

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andk pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/mynewt-nimble.git

commit c995fe4fc40cfdb0967c98bff53f7d0bcc36030e
Author: Andrzej Kaczmarek <an...@codecoup.pl>
AuthorDate: Tue Jan 31 11:23:20 2023 +0100

    nimble/ll: Optimize num used channels calculation
    
    popcount calculates number of bits set without loop.
---
 nimble/controller/src/ble_ll_utils.c | 17 ++---------------
 1 file changed, 2 insertions(+), 15 deletions(-)

diff --git a/nimble/controller/src/ble_ll_utils.c b/nimble/controller/src/ble_ll_utils.c
index 3603742d..5d023b11 100644
--- a/nimble/controller/src/ble_ll_utils.c
+++ b/nimble/controller/src/ble_ll_utils.c
@@ -253,21 +253,8 @@ ble_ll_utils_remapped_channel(uint8_t remap_index, const uint8_t *chanmap)
 uint8_t
 ble_ll_utils_calc_num_used_chans(const uint8_t *chan_map)
 {
-    uint32_t u32 = 0;
-    uint32_t num_used_chans = 0;
-    unsigned idx;
-
-    for (idx = 0; idx < 37; idx++) {
-        if ((idx % 8) == 0) {
-            u32 = chan_map[idx / 8];
-        }
-        if (u32 & 1) {
-            num_used_chans++;
-        }
-        u32 >>= 1;
-    }
-
-    return num_used_chans;
+    return __builtin_popcountll(((uint64_t)(chan_map[4] & 0x1f) << 32) |
+                                get_le32(chan_map));
 }
 
 #if MYNEWT_VAL(BLE_LL_CFG_FEAT_LE_CSA2)