Initial implementation of XAP protocol.

quantum/xap/xap.c

@@ -0,0 +1,116 @@
+/* Copyright 2021 Nick Brassel (@tzarc)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <quantum.h>
+#include <xap.h>
+#include <usb_descriptor.h>
+
+#define QSTR2(z) #z
+#define QSTR(z) QSTR2(z)
+
+typedef enum xap_route_type_t {
+    XAP_UNUSED = 0,  // "Unused" needs to be zero -- undefined routes (through preprocessor) will be skipped
+    XAP_ROUTE,
+    XAP_EXECUTE,
+    XAP_VALUE,
+    XAP_GETTER,
+    XAP_CONST_MEM,
+    TOTAL_XAP_ROUTE_TYPES
+} xap_route_type_t;
+
+#define XAP_ROUTE_TYPE_BIT_COUNT 3
+
+typedef struct __attribute__((packed)) xap_route_flags_t {
+    xap_route_type_t type : XAP_ROUTE_TYPE_BIT_COUNT;
+    uint8_t          is_secure : 1;
+} xap_route_flags_t;
+
+_Static_assert(TOTAL_XAP_ROUTE_TYPES <= (1 << (XAP_ROUTE_TYPE_BIT_COUNT)), "Number of XAP route types is too large for XAP_ROUTE_TYPE_BITS.");
+_Static_assert(sizeof(xap_route_flags_t) == 1, "xap_route_flags_t is not length of 1");
+
+typedef struct xap_route_t xap_route_t;
+struct __attribute__((packed)) xap_route_t {
+    const xap_route_flags_t flags;
+    union {
+        // XAP_ROUTE
+        struct {
+            const xap_route_t *child_routes;
+            const uint8_t      child_routes_len;
+        };
+
+        // XAP_EXECUTE
+        bool (*handler)(xap_token_t token, const uint8_t *data, size_t data_len);
+
+        // XAP_VALUE
+        uint32_t u32value;
+
+        // XAP_GETTER
+        uint32_t (*u32getter)(void);
+
+        // XAP_CONST_MEM
+        struct {
+            const void *  const_data;
+            const uint8_t const_data_len;
+        };
+    };
+};
+
+#include <xap_generated.inl>
+
+void xap_execute_route(xap_token_t token, const xap_route_t *routes, size_t max_routes, const uint8_t *data, size_t data_len) {
+    if (data_len == 0) return;
+    xap_identifier_t id = data[0];
+
+    if (id < max_routes) {
+        xap_route_t route;
+        memcpy_P(&route, &routes[id], sizeof(xap_route_t));
+        switch (route.flags.type) {
+            case XAP_ROUTE:
+                if (route.child_routes != NULL && route.child_routes_len > 0 && data_len > 0) {
+                    xap_execute_route(token, route.child_routes, route.child_routes_len, &data[1], data_len - 1);
+                    return;
+                }
+                break;
+
+            case XAP_EXECUTE:
+                if (route.handler != NULL) {
+                    bool ok = (route.handler)(token, data_len == 1 ? NULL : &data[1], data_len - 1);
+                    if (ok) return;
+                }
+                break;
+
+            case XAP_VALUE:
+                xap_respond_u32(token, route.u32value);
+                return;
+
+            case XAP_GETTER:
+                xap_respond_u32(token, (route.u32getter)());
+                return;
+
+            case XAP_CONST_MEM:
+                xap_respond_data_P(token, route.const_data, route.const_data_len);
+                return;
+
+            default:
+                break;
+        }
+    }
+
+    // Nothing got handled, so we respond with failure.
+    xap_respond_failure(token, XAP_RESPONSE_FLAG_FAILED);
+}
+
+void xap_receive(xap_token_t token, const uint8_t *data, size_t length) { xap_execute_route(token, xap_route_table, sizeof(xap_route_table) / sizeof(xap_route_t), data, length); }