From 9427aeb58cdfe72a53e58acbd1242fc681878cd5 Mon Sep 17 00:00:00 2001
From: Matthias Ringwald <matthias@ringwald.ch>
Date: Thu, 31 Aug 2023 15:03:58 +0200
Subject: [PATCH] hci: replace hci_get_sco_packet_length with
 hci_get_sco_packet_length_for_connection

---
 src/hci.c | 52 ++++++++++++++++++++++++++++++++++------------------
 src/hci.h | 10 +++++++++-
 2 files changed, 43 insertions(+), 19 deletions(-)

diff --git a/src/hci.c b/src/hci.c
index 3a2fe8f38..ad4bb6662 100644
--- a/src/hci.c
+++ b/src/hci.c
@@ -9279,14 +9279,9 @@ static int hci_have_usb_transport(void){
     return (transport_name[0] == 'H') && (transport_name[1] == '2');
 }
 
-/** @brief Get SCO packet length for current SCO Voice setting
- *  @note  Using SCO packets of the exact length is required for USB transfer
- *  @return Length of SCO packets in bytes (not audio frames)
- */
-uint16_t hci_get_sco_packet_length(void){
+static uint16_t hci_sco_packet_length_for_payload_length(uint16_t payload_size){
     uint16_t sco_packet_length = 0;
 
-#ifdef ENABLE_SCO_OVER_HCI
     // Transparent = mSBC => 1, CVSD with 16-bit samples requires twice as much bytes
     int multiplier;
     if (((hci_stack->sco_voice_setting_active & 0x03) != 0x03) &&
@@ -9295,31 +9290,52 @@ uint16_t hci_get_sco_packet_length(void){
     } else {
         multiplier = 1;
     }
-
-
+#ifdef ENABLE_SCO_OVER_HCI
     if (hci_have_usb_transport()){
-        // see Core Spec for H2 USB Transfer. 
+        // see Core Spec for H2 USB Transfer.
         // 3 byte SCO header + 24 bytes per connection
-        int num_sco_connections = btstack_max(1, hci_number_sco_connections());
-        sco_packet_length = 3 + 24 * num_sco_connections * multiplier;
+        // @note multiple sco connections not supported currently
+        sco_packet_length = 3 + 24 * multiplier;
     } else {
-        // 3 byte SCO header + SCO packet size over the air (60 bytes)
-        sco_packet_length = 3 + 60 * multiplier;
+        // 3 byte SCO header + SCO packet length over the air
+        sco_packet_length = 3 + payload_size * multiplier;
         // assert that it still fits inside an SCO buffer
         if (sco_packet_length > (hci_stack->sco_data_packet_length + 3)){
-            sco_packet_length = 3 + 60;
+            sco_packet_length = 3 + hci_stack->sco_data_packet_length;
         }
     }
 #endif
-
 #ifdef HAVE_SCO_TRANSPORT
-    // Transparent = mSBC => 1, CVSD with 16-bit samples requires twice as much bytes
-    int multiplier = ((hci_stack->sco_voice_setting_active & 0x03) == 0x03) ? 1 : 2;
-    sco_packet_length = 3 + 60 * multiplier;
+    // 3 byte SCO header + SCO packet length over the air
+    sco_packet_length = 3 + payload_size * multiplier;
+    // assert that it still fits inside an SCO buffer
+    if (sco_packet_length > (hci_stack->sco_data_packet_length + 3)){
+        sco_packet_length = 3 + hci_stack->sco_data_packet_length;
+    }
 #endif
     return sco_packet_length;
 }
 
+uint16_t hci_get_sco_packet_length_for_connection(hci_con_handle_t sco_con_handle){
+    hci_connection_t * connection = hci_connection_for_handle(sco_con_handle);
+    if (connection != NULL){
+        return hci_sco_packet_length_for_payload_length(connection->sco_payload_length);
+    }
+    return 0;
+}
+
+uint16_t hci_get_sco_packet_length(void){
+    btstack_linked_list_iterator_t it;
+    btstack_linked_list_iterator_init(&it, &hci_stack->connections);
+    while (btstack_linked_list_iterator_has_next(&it)){
+        hci_connection_t * connection = (hci_connection_t *) btstack_linked_list_iterator_next(&it);
+        if ( connection->address_type == BD_ADDR_TYPE_SCO ) {
+            return hci_sco_packet_length_for_payload_length(connection->sco_payload_length);;
+        }
+    }
+    return 0;
+}
+
 /**
 * @brief Sets the master/slave policy
 * @param policy (0: attempt to become master, 1: let connecting device decide)
diff --git a/src/hci.h b/src/hci.h
index 7947cd810..e37c9b343 100644
--- a/src/hci.h
+++ b/src/hci.h
@@ -1446,7 +1446,15 @@ uint8_t hci_send_cmd(const hci_cmd_t * cmd, ...);
 
 // Sending SCO Packets
 
-/** @brief Get SCO packet length for current SCO Voice setting
+/** @brief Get SCO payload length for existing SCO connection and current SCO Voice setting
+ *  @note  Using SCO packets of the exact length is required for USB transfer in general and some H4 controllers as well
+ *  @param sco_con_handle
+ *  @return Length of SCO payload in bytes (not audio frames) incl. 3 byte header
+ */
+uint16_t hci_get_sco_packet_length_for_connection(hci_con_handle_t sco_con_handle);
+
+/** @brief Get SCO packet length for one of the existing SCO connections and current SCO Voice setting
+ *  @deprecated Please use hci_get_sco_packet_length_for_connection instead
  *  @note  Using SCO packets of the exact length is required for USB transfer
  *  @return Length of SCO packets in bytes (not audio frames) incl. 3 byte header
  */