btstack_hid_parser: add function that calculates report size for given report type and ID from report descriptor

src/btstack_hid_parser.c

@@ -54,50 +54,6 @@
  *  btstack_hid_parser.c
  */
 
-
-typedef enum {
-    Main=0,
-    Global,
-    Local,
-    Reserved
-} TagType;
-
-typedef enum {
-    Input=8,
-    Output,
-    Coll,
-    Feature,
-    EndColl
-} MainItemTag;
-
-typedef enum {
-    UsagePage,
-    LogicalMinimum,
-    LogicalMaximum,
-    PhysicalMinimum,
-    PhysicalMaximum,
-    UnitExponent,
-    Unit,
-    ReportSize,
-    ReportID,
-    ReportCount,
-    Push,
-    Pop
-} GlobalItemTag;
-
-typedef enum {
-    Usage,
-    UsageMinimum,
-    UsageMaximum,
-    DesignatorIndex,
-    DesignatorMinimum,
-    DesignatorMaximum,
-    StringIndex,
-    StringMinimum,
-    StringMaximum,
-    Delimiter 
-} LocalItemTag;
-
 const int hid_item_sizes[] = { 0, 1, 2, 4 };
 
 #ifdef HID_PARSER_PRETTY_PRINT
@@ -193,7 +149,7 @@ static void hid_pretty_print_item(btstack_hid_parser_t * parser, hid_descriptor_
 }
 
 // parse descriptor item and read up to 32-bit bit value
-static void btstack_hid_parse_descriptor_item(hid_descriptor_item_t * item, const uint8_t * hid_descriptor, uint16_t hid_descriptor_len){
+void btstack_hid_parse_descriptor_item(hid_descriptor_item_t * item, const uint8_t * hid_descriptor, uint16_t hid_descriptor_len){
     // parse item header
     if (hid_descriptor_len < 1) return;
     uint16_t pos = 0;
@@ -451,3 +407,65 @@ void btstack_hid_parser_get_field(btstack_hid_parser_t * parser, uint16_t * usag
         }
     }
 }
+
+int btstack_hid_get_report_size_for_id(int report_id, btstack_hid_report_type_t report_type, uint16_t hid_descriptor_len, const uint8_t * hid_descriptor){
+    int total_report_size = 0;
+    int report_size = 0;
+    int report_count = 0;
+    int current_report_id = 0;
+    
+    while (hid_descriptor_len){
+        int valid_report_type = 0;
+        hid_descriptor_item_t item;
+        // printf("item: 0x%02x (%p)\n", *hid_descriptor, hid_descriptor);
+        btstack_hid_parse_descriptor_item(&item, hid_descriptor, hid_descriptor_len);
+        switch (item.item_type){
+            case Global:
+                switch ((GlobalItemTag)item.item_tag){
+                    case ReportID:
+                        current_report_id = item.item_value;
+                        break;
+                    case ReportCount:
+                        if (current_report_id != report_id) break;
+                        report_count = item.item_value;
+                        break;
+                    case ReportSize:
+                        if (current_report_id != report_id) break;
+                        report_size = item.item_value;
+                        break;
+                    default:
+                        break;
+                }
+                break;
+            case Main:  
+                if (current_report_id != report_id) break;
+                // printf("tag %d, report_type %d\n", item.item_tag, report_type);
+                switch ((MainItemTag)item.item_tag){
+                    case Input:
+                        if (report_type != BTSTACK_HID_REPORT_TYPE_INPUT) break;
+                        valid_report_type = 1;
+                        break;
+                    case Output:
+                        if (report_type != BTSTACK_HID_REPORT_TYPE_OUTPUT) break;
+                        valid_report_type = 1;
+                        break;
+                    case Feature:
+                        if (report_type != BTSTACK_HID_REPORT_TYPE_FEATURE) break;
+                        valid_report_type = 1;
+                        break;
+                    default:
+                        break;
+                }
+                if (!valid_report_type) break;
+                total_report_size += report_count * report_size;
+                report_size = 0;
+                report_count = 0;
+                break;
+            default:
+                break;
+        }
+        hid_descriptor_len -= item.item_size;
+        hid_descriptor += item.item_size;
+    }
+    return (total_report_size + 7)/8;
+}

src/btstack_hid_parser.h

@@ -50,6 +50,49 @@
 extern "C" {
 #endif
 
+typedef enum {
+    Main=0,
+    Global,
+    Local,
+    Reserved
+} TagType;
+
+typedef enum {
+    Input=8,
+    Output,
+    Coll,
+    Feature,
+    EndColl
+} MainItemTag;
+
+typedef enum {
+    UsagePage,
+    LogicalMinimum,
+    LogicalMaximum,
+    PhysicalMinimum,
+    PhysicalMaximum,
+    UnitExponent,
+    Unit,
+    ReportSize,
+    ReportID,
+    ReportCount,
+    Push,
+    Pop
+} GlobalItemTag;
+
+typedef enum {
+    Usage,
+    UsageMinimum,
+    UsageMaximum,
+    DesignatorIndex,
+    DesignatorMinimum,
+    DesignatorMaximum,
+    StringIndex,
+    StringMinimum,
+    StringMaximum,
+    Delimiter 
+} LocalItemTag;
+
 typedef struct  {
     int32_t  item_value;    
     uint16_t item_size; 
@@ -140,6 +183,22 @@ int  btstack_hid_parser_has_more(btstack_hid_parser_t * parser);
  */
 void btstack_hid_parser_get_field(btstack_hid_parser_t * parser, uint16_t * usage_page, uint16_t * usage, int32_t * value);
 
+/**
+ * @brief Parses descriptor item
+ * @param item
+ * @param hid_descriptor
+ * @param hid_descriptor_len
+ */
+void btstack_hid_parse_descriptor_item(hid_descriptor_item_t * item, const uint8_t * hid_descriptor, uint16_t hid_descriptor_len);
+
+/**
+ * @brief Parses descriptor and returns report size for given report ID and report type
+ * @param report_id
+ * @param report_type
+ * @param hid_descriptor_len
+ * @param hid_descriptor
+ */
+int btstack_hid_get_report_size_for_id(int report_id, btstack_hid_report_type_t report_type, uint16_t hid_descriptor_len, const uint8_t * hid_descriptor);
 /* API_END */
 
 #if defined __cplusplus

test/hid_parser/.gitignore

@@ -0,0 +1 @@
+hid_parser_test

test/hid_parser/hid_parser_test.c

@@ -218,6 +218,8 @@ const uint8_t keyboard_report1[] = { 0x01, 0x00, 0x04, 0x05, 0x06, 0x00, 0x00, 0
 const uint8_t combo_report1[]    = { 0x01, 0x03, 0x02, 0x03 };
 const uint8_t combo_report2[]    = { 0x02, 0x01, 0x00,  0x04, 0x05, 0x06, 0x00, 0x00, 0x00 };
 
+
+
 static void expect_field(btstack_hid_parser_t * parser, uint16_t expected_usage_page, uint16_t expected_usage, int32_t expected_value){
     // printf("expected - usage page %02x, usage %04x, value %02x (bit pos %u)\n", expected_usage_page, expected_usage, expected_value, parser->report_pos_in_bit);
     CHECK_EQUAL(1, btstack_hid_parser_has_more(parser));
@@ -326,6 +328,22 @@ TEST(HID, Combo2){
     CHECK_EQUAL(0, btstack_hid_parser_has_more(&hid_parser));
 }
 
+TEST(HID, GetReportSize){
+    int report_size = 0;
+    const uint8_t * hid_descriptor =  combo_descriptor_with_report_ids;
+    uint16_t hid_descriptor_len = sizeof(combo_descriptor_with_report_ids);
+    // report_size = btstack_hid_get_report_size_for_id(1, BTSTACK_HID_REPORT_TYPE_INPUT, hid_descriptor_len, hid_descriptor);
+    // CHECK_EQUAL(3, report_size);
+
+    hid_descriptor = hid_descriptor_keyboard_boot_mode;
+    hid_descriptor_len = sizeof(hid_descriptor_keyboard_boot_mode);
+    report_size = btstack_hid_get_report_size_for_id(0, BTSTACK_HID_REPORT_TYPE_OUTPUT, hid_descriptor_len, hid_descriptor);
+    CHECK_EQUAL(1, report_size);
+    report_size = btstack_hid_get_report_size_for_id(0, BTSTACK_HID_REPORT_TYPE_INPUT, hid_descriptor_len, hid_descriptor);
+    CHECK_EQUAL(8, report_size);
+}
+
+
 int main (int argc, const char * argv[]){
     // hci_dump_open("hci_dump.pklg", HCI_DUMP_PACKETLOGGER);
     return CommandLineTestRunner::RunAllTests(argc, argv);