gdb: Prepare watchpoints_t data structure

In preparation for the watchpoint implementation define an
avr_gdb_watchpoints_t struct to handle both. The struct is only accessed
through gdb_watch_* functions, therefore changing its internals should
be easy.

Note that this implementation cannot handle different watchpoints at the
same address with a different size.

The avr_gdb_watch_type enum is public and will be used in sim_core.c in
a follow-up commit.

diff --git a/simavr/sim/sim_gdb.c b/simavr/sim/sim_gdb.c
index bde9131..a69bbf1 100644 (file)
--- a/simavr/sim/sim_gdb.c
+++ b/simavr/sim/sim_gdb.c
@@ -38,20 +38,97 @@
 
 #define DBG(w)
 
+#define WATCH_LIMIT (32)
+
+typedef struct {
+       uint32_t len; /**< How many points are taken (points[0] .. points[len - 1]). */
+       struct {
+               uint32_t addr; /**< Which address is watched. */
+               uint32_t size; /**< How large is the watched segment. */
+               uint32_t kind; /**< Bitmask of enum avr_gdb_watch_type values. */
+       } points[WATCH_LIMIT];
+} avr_gdb_watchpoints_t;
+
 typedef struct avr_gdb_t {
        avr_t * avr;
        int             listen; // listen socket
        int             s;              // current gdb connection
 
-       uint32_t        watchmap;
-       struct {
-               avr_flashaddr_t pc;
-               uint32_t        len;
-               int kind;
-       } watch[32];
+       avr_gdb_watchpoints_t breakpoints;
 } avr_gdb_t;
 
 
+/**
+ * Returns the index of the watchpoint if found, -1 otherwise.
+ */
+static int gdb_watch_find(const avr_gdb_watchpoints_t * w, uint32_t addr)
+{
+       for (int i = 0; i < w->len; i++) {
+               if (w->points[i].addr == addr) {
+                       return i;
+               }
+       }
+
+       return -1;
+}
+
+/**
+ * Returns -1 on error, 0 otherwise.
+ */
+static int gdb_watch_add_or_update(avr_gdb_watchpoints_t * w, enum avr_gdb_watch_type kind, uint32_t addr,
+               uint32_t size)
+{
+       /* If the watchpoint exists, update it. */
+       int i = gdb_watch_find(w, addr);
+       if (i != -1) {
+               w->points[i].size = size;
+               w->points[i].kind |= kind;
+               return 0;
+       }
+
+       /* Otherwise add it. */
+       if (w->len == WATCH_LIMIT) {
+               return -1;
+       }
+
+       w->points[w->len].kind = kind;
+       w->points[w->len].addr = addr;
+       w->points[w->len].size = size;
+
+       w->len++;
+
+       return 0;
+}
+
+/**
+ * Returns -1 on error or if the specified point does not exist, 0 otherwise.
+ */
+static int gdb_watch_rm(avr_gdb_watchpoints_t * w, enum avr_gdb_watch_type kind, uint32_t addr)
+{
+       int i = gdb_watch_find(w, addr);
+       if (i == -1) {
+               return -1;
+       }
+
+       w->points[i].kind &= ~kind;
+       if (w->points[i].kind) {
+               return 0;
+       }
+
+       for (i = i + 1; i < w->len; i++) {
+               w->points[i - 1] = w->points[i];
+       }
+
+       w->len--;
+
+       return 0;
+}
+
+static void gdb_watch_clear(avr_gdb_watchpoints_t * w)
+{
+       w->len = 0;
+}
+
 static void gdb_send_reply(avr_gdb_t * g, char * cmd)
 {
        uint8_t reply[1024];
@@ -78,37 +155,17 @@ static void gdb_send_quick_status(avr_gdb_t * g, uint8_t signal)
        gdb_send_reply(g, cmd);
 }
 
-static int gdb_change_breakpoint(avr_gdb_t * g, int set, int kind, avr_flashaddr_t addr, uint32_t len)
+static int gdb_change_breakpoint(avr_gdb_watchpoints_t * w, int set, enum avr_gdb_watch_type kind,
+               uint32_t addr, uint32_t size)
 {
-       DBG(printf("set %d kind %d addr %08x len %d (map %08x)\n", set, kind, addr, len, g->watchmap);)
+       DBG(printf("set %d kind %d addr %08x len %d\n", set, kind, addr, len);)
+
        if (set) {
-               if (g->watchmap == 0xffffffff)
-                       return -1;      // map full
-
-               // check to see if it exists
-               for (int i = 0; i < 32; i++)
-                       if ((g->watchmap & (1 << i)) && g->watch[i].pc == addr) {
-                               g->watch[i].len = len;
-                               return 0;
-                       }
-               for (int i = 0; i < 32; i++)
-                       if (!(g->watchmap & (1 << i))) {
-                               g->watchmap |= (1 << i);
-                               g->watch[i].len = len;
-                               g->watch[i].pc = addr;
-                               g->watch[i].kind = kind;
-                               return 0;
-                       }
+               return gdb_watch_add_or_update(w, kind, addr, size);
        } else {
-               for (int i = 0; i < 32; i++)
-                       if ((g->watchmap & (1 << i)) && g->watch[i].pc == addr) {
-                               g->watchmap &= ~(1 << i);
-                               g->watch[i].len = 0;
-                               g->watch[i].pc = 0;
-                               g->watch[i].kind = 0;
-                               return 0;
-                       }
+               return gdb_watch_rm(w, kind, addr);
        }
+
        return -1;
 }
 
@@ -266,18 +323,19 @@ static void gdb_handle_command(avr_gdb_t * g, char * cmd)
                case 'Z':       // set clear break/watchpoint
                case 'z': {
                        uint32_t kind, addr, len;
+                       int set = (command == 'Z');
                        sscanf(cmd, "%d,%x,%x", &kind, &addr, &len);
 //                     printf("breakpoint %d, %08x, %08x\n", kind, addr, len);
                        switch (kind) {
                                case 0: // software breakpoint
                                case 1: // hardware breakpoint
-                                       if (addr <= avr->flashend) {
-                                               if (gdb_change_breakpoint(g, command == 'Z', kind, addr, len))
-                                                       gdb_send_reply(g, "E01");
-                                               else
-                                                       gdb_send_reply(g, "OK");
-                                       } else
-                                               gdb_send_reply(g, "E01");               // out of flash address
+                                       if (addr > avr->flashend ||
+                                                       gdb_change_breakpoint(&g->breakpoints, set, 1 << kind, addr, len) == -1) {
+                                               gdb_send_reply(g, "E01");
+                                               break;
+                                       }
+
+                                       gdb_send_reply(g, "OK");
                                        break;
                                // TODO
                                case 2: // write watchpoint
@@ -334,7 +392,7 @@ static int gdb_network_handler(avr_gdb_t * g, uint32_t dosleep)
                if (r == 0) {
                        printf("%s connection closed\n", __FUNCTION__);
                        close(g->s);
-                       g->watchmap = 0;                                // clear breakpoints
+                       gdb_watch_clear(&g->breakpoints);
                        g->avr->state = cpu_Running;    // resume
                        g->s = -1;
                        return 1;
@@ -380,15 +438,11 @@ int avr_gdb_processor(avr_t * avr, int sleep)
                return 0;       
        avr_gdb_t * g = avr->gdb;
 
-       if (g->watchmap && avr->state == cpu_Running) {
-               for (int i = 0; i < 32; i++)
-                       if ((g->watchmap & (1 << i)) && g->watch[i].pc == avr->pc) {
-                               DBG(printf("avr_gdb_processor hit breakpoint at %08x\n", avr->pc);)
-                               gdb_send_quick_status(g, 0);
-                               avr->state = cpu_Stopped;
-                       }               
-       }
-       if (avr->state == cpu_StepDone) {
+       if (avr->state == cpu_Running && gdb_watch_find(&g->breakpoints, avr->pc) != -1) {
+               DBG(printf("avr_gdb_processor hit breakpoint at %08x\n", avr->pc);)
+               gdb_send_quick_status(g, 0);
+               avr->state = cpu_Stopped;
+       } else if (avr->state == cpu_StepDone) {
                gdb_send_quick_status(g, 0);
                avr->state = cpu_Stopped;
        }

diff --git a/simavr/sim/sim_gdb.h b/simavr/sim/sim_gdb.h
index bb955ae..a9e8aa4 100644 (file)
--- a/simavr/sim/sim_gdb.h
+++ b/simavr/sim/sim_gdb.h
@@ -26,6 +26,17 @@
 extern "C" {
 #endif
 
+/* Watchpoint types.
+   See GDB User Manual, Appendix E.2 */
+enum avr_gdb_watch_type {
+       AVR_GDB_BREAK_SOFT   = 1 << 0,
+       AVR_GDB_BREAK_HARD   = 1 << 1,
+
+       AVR_GDB_WATCH_WRITE  = 1 << 2,
+       AVR_GDB_WATCH_READ   = 1 << 3,
+       AVR_GDB_WATCH_ACCESS = AVR_GDB_WATCH_WRITE | AVR_GDB_WATCH_READ,
+};
+
 int avr_gdb_init(avr_t * avr);
 
 // call from the main AVR decoder thread