Implement breakpoints (untested)

include/server.h

@@ -6,13 +6,30 @@
 #include <stdbool.h>
 #include <vb.h>
 
+typedef enum rdb_server_stop_reason_t {
+    /* not even stopped */
+    stop_reason_none,
+    /* we are stepping */
+    stop_reason_trace,
+    /* we hit an actual breakpoint */
+    stop_reason_breakpoint,
+    /* the user hit pause */
+    stop_reason_trap,
+    /* some opcode is not implemented */
+    stop_reason_not_implemented
+} rdb_server_stop_reason_t;
+
+#define RDB_SERVER_MAX_BREAKPOINTS 16
 typedef struct RdbServer {
     VB *sim;
     bool running;
+    uint32_t brks[RDB_SERVER_MAX_BREAKPOINTS];
+    uint32_t brkslen;
+    rdb_server_stop_reason_t stopreason;
 } RdbServer;
 
 void rdbServerInit(RdbServer *srv, VB *sim);
 int rdbServerHandleCommand(RdbServer *srv, CommandBuf *cmd, RdbResponse *res);
-int rdbServerBreak(RdbServer *srv, RdbResponse *res);
+int rdbServerSendStopPacket(RdbServer *srv, RdbResponse *res);
 
 #endif

main.c

@@ -48,13 +48,15 @@ int server(int connfd, VB *sim) {
                 cycles = MAX_STEP_CYCLES;
                 brk = vbEmulate(sim, &cycles);
                 if (brk) {
-                    /* We hit a breakpoint */ 
+                    /* We stopped for some reason */ 
                     if (brk == -1) {
-                        /* actually, not implemented */
-                        rdbServerBreak(&srv, &res);
-                    } else {
-                        fprintf(stderr, "surprising response %d from vbEmulate\n", brk);
-                        return -1;
+                        /* the reason was "opcode not implemented" */
+                        srv.running = false;
+                        srv.stopreason = stop_reason_not_implemented;
+                    }
+                    result = rdbServerSendStopPacket(&srv, &res);
+                    if (result != 0) {
+                        return result;
                     }
                 } else {
                     sleepNanos((MAX_STEP_CYCLES - cycles) * 50);
@@ -139,11 +141,9 @@ int main(int argc, char** argv) {
         return 1;
     }
     /* relevant state at the start of the physics sim's main */
-    /*
     vbSetProgramCounter(sim, 0x070002ba);
     vbSetProgramRegister(sim, 3, 0x0500ffc0);
     vbSetProgramRegister(sim, 4, 0x05008000);
-    */
 
     if (argc > 2) {
         char *end;

request.c

@@ -8,6 +8,7 @@
 void rdbRequestInit(RdbRequest *req, int connfd, char *buf, size_t buflen) {
     req->connfd = connfd;
     req->outbuf = buf;
+    req->outbuflen = buflen;
     req->blocking = true;
     rdbRequestReset(req);
 }

server.c

@@ -69,9 +69,59 @@ const uint32_t SYSTEM_REGISTERS[] = {
 
 const uint32_t PC_INDEX = 32 + 13;
 
+/* TODO: this should use userdata */
+static void *SERVER_POINTER;
+static int onExecute(VB *sim, uint32_t address, const uint16_t *code, int length) {
+    uint32_t i;
+    RdbServer *srv = SERVER_POINTER;
+
+    (void)sim;
+    (void)code;
+    (void)length;
+    for (i = 0; i < srv->brkslen; ++i) {
+        if (srv->brks[i] == address) {
+            srv->stopreason = stop_reason_breakpoint;
+            return 1;
+        }
+    }
+    return 0;
+}
+
+static bool addBreakpoint(RdbServer *srv, uint32_t address) {
+    uint32_t i;
+    for (i = 0; i < srv->brkslen; ++i) {
+        if (srv->brks[i] == address) {
+            /* This breakpoint is already set */
+            return true;
+        }
+    }
+    if (i == RDB_SERVER_MAX_BREAKPOINTS) {
+        /* We've added too many breakpoints */
+        return false;
+    }
+    srv->brks[i] = address;
+    ++srv->brkslen;
+    return true;
+}
+
+static void removeBreakpoint(RdbServer *srv, uint32_t address) {
+    uint32_t i;
+    for (i = 0; i < srv->brkslen; ++i) {
+        if (srv->brks[i] == address) {
+            srv->brks[i] = srv->brks[srv->brkslen - 1];
+            --srv->brkslen;
+            return;
+        }
+    }
+}
+
 void rdbServerInit(RdbServer *srv, VB *sim) {
     srv->sim = sim;
     srv->running = false;
+    srv->brkslen = 0;
+    srv->stopreason = stop_reason_none;
+    SERVER_POINTER = srv;
+    vbSetCallback(sim, VB_EXECUTE, (void*)(uint64_t)&onExecute);
 }
 
 int rdbServerHandleCommand(RdbServer *srv, CommandBuf *cmd, RdbResponse *res) {
@@ -199,21 +249,19 @@ int rdbServerHandleCommand(RdbServer *srv, CommandBuf *cmd, RdbResponse *res) {
         /* The debugger has told us to run until we are stopped. */
         /* Don't send a response to this until we receive an ETX (when the debugger pauses us). */
         srv->running = true;
+        srv->stopreason = stop_reason_none;
         return 0;
     }
     if (cmdMatchStr(cmd, "\x03")) {
         /* Received an ETX, indicating that the server wants to cancel the "c" command from before. */
         srv->running = false;
+        srv->stopreason = stop_reason_trap;
         /* Send the response to the "c" command from before. */
-        rdbResponseWriteStr(res, "T05thread:p1.t1;threads:p1.t1");
-        return rdbResponseSendPacket(res);
+        return rdbServerSendStopPacket(srv, res);
     }
     if (cmdMatchStr(cmd, "?")) {
         /* The debugger has asked us why we stopped */
-        rdbResponseWriteStr(res, "T");
-        rdbResponseWriteStr(res, srv->running ? "00" : "05");
-        rdbResponseWriteStr(res, "thread:p1.t1;threads:p1.t1;");
-        return rdbResponseSendPacket(res);
+        return rdbServerSendStopPacket(srv, res);
     }
     if (cmdMatchStr(cmd, "m")) {
         /* read memory */
@@ -244,14 +292,55 @@ int rdbServerHandleCommand(RdbServer *srv, CommandBuf *cmd, RdbResponse *res) {
         rdbResponseWriteStr(res, "OK");
         return rdbResponseSendPacket(res);
     }
+    if (cmdMatchStr(cmd, "Z0,")) {
+        /* set a breakpoint */
+        uint32_t address;
+        if (!cmdMatchHexNumber(cmd, &address)) return -1;
+        if (!cmdMatchStr(cmd, ",0")) return -1;
+
+        if (!addBreakpoint(srv, address)) return -1;
+        rdbResponseWriteStr(res, "OK");
+        return rdbResponseSendPacket(res);
+    }
+    if (cmdMatchStr(cmd, "z0,")) {
+        /* remove a breakpoint */
+        uint32_t address;
+        if (!cmdMatchHexNumber(cmd, &address)) return -1;
+        if (!cmdMatchStr(cmd, ",0")) return -1;
+
+        removeBreakpoint(srv, address);
+        rdbResponseWriteStr(res, "OK");
+        return rdbResponseSendPacket(res);
+    }
     fprintf(stderr, "Unrecognized command.\n");
     return rdbResponseSendPacket(res);
 }
 
-int rdbServerBreak(RdbServer *srv, RdbResponse *res) {
-    srv->running = false;
+int rdbServerSendStopPacket(RdbServer *srv, RdbResponse *res) {
     rdbResponseBeginPacket(res);
-    rdbResponseWriteStr(res, "T05:thread:p1.t1;threads:p1.t1;");
+    switch (srv->stopreason) {
+    case stop_reason_trace:
+    case stop_reason_none:
+        rdbResponseWriteStr(res, "T00");
+        break;
+    default:
+        rdbResponseWriteStr(res, "T05");
+    }
+    rdbResponseWriteStr(res, "thread:p1.t1;threads:p1.t1;");
+    switch (srv->stopreason) {
+    case stop_reason_trace:
+        rdbResponseWriteStr(res, "reason:trace;");
+        break;
+    case stop_reason_breakpoint:
+        rdbResponseWriteStr(res, "reason:breakpoint;");
+        break;
+    case stop_reason_trap:
+        rdbResponseWriteStr(res, "reason:trap;");
+        break;
+    case stop_reason_not_implemented:
+        rdbResponseWriteStr(res, "reason:exception;description:opcode not implemented;");
+        break;
+    default: break;
+    }
     return rdbResponseSendPacket(res);
 }
-