target-ppc: extract register length calculation in gdbstub

This patch extracts the method to determine a register's size
into a separate function.

Reviewed-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Thomas Falcon <tlfalcon@linux.vnet.ibm.com>
Signed-off-by: Alexander Graf <agraf@suse.de>

target-ppc/gdbstub.c

@@ -21,6 +21,44 @@
 #include "qemu-common.h"
 #include "exec/gdbstub.h"
 
+static int ppc_gdb_register_len(int n)
+{
+    switch (n) {
+    case 0 ... 31:
+        /* gprs */
+        return sizeof(target_ulong);
+    case 32 ... 63:
+        /* fprs */
+        if (gdb_has_xml) {
+            return 0;
+        }
+        return 8;
+    case 66:
+        /* cr */
+        return 4;
+    case 64:
+        /* nip */
+    case 65:
+        /* msr */
+    case 67:
+        /* lr */
+    case 68:
+        /* ctr */
+    case 69:
+        /* xer */
+        return sizeof(target_ulong);
+    case 70:
+        /* fpscr */
+        if (gdb_has_xml) {
+            return 0;
+        }
+        return sizeof(target_ulong);
+    default:
+        return 0;
+    }
+}
+
+
 /* Old gdb always expects FP registers.  Newer (xml-aware) gdb only
  * expects whatever the target description contains.  Due to a
  * historical mishap the FP registers appear in between core integer
@@ -32,100 +70,99 @@ int ppc_cpu_gdb_read_register(CPUState *cs, uint8_t *mem_buf, int n)
 {
     PowerPCCPU *cpu = POWERPC_CPU(cs);
     CPUPPCState *env = &cpu->env;
+    int r = ppc_gdb_register_len(n);
+
+    if (!r) {
+        return r;
+    }
 
     if (n < 32) {
         /* gprs */
-        return gdb_get_regl(mem_buf, env->gpr[n]);
+        gdb_get_regl(mem_buf, env->gpr[n]);
     } else if (n < 64) {
         /* fprs */
-        if (gdb_has_xml) {
-            return 0;
-        }
         stfq_p(mem_buf, env->fpr[n-32]);
-        return 8;
     } else {
         switch (n) {
         case 64:
-            return gdb_get_regl(mem_buf, env->nip);
+            gdb_get_regl(mem_buf, env->nip);
+            break;
         case 65:
-            return gdb_get_regl(mem_buf, env->msr);
+            gdb_get_regl(mem_buf, env->msr);
+            break;
         case 66:
             {
                 uint32_t cr = 0;
                 int i;
                 for (i = 0; i < 8; i++) {
                     cr |= env->crf[i] << (32 - ((i + 1) * 4));
                 }
-                return gdb_get_reg32(mem_buf, cr);
+                gdb_get_reg32(mem_buf, cr);
+                break;
             }
         case 67:
-            return gdb_get_regl(mem_buf, env->lr);
+            gdb_get_regl(mem_buf, env->lr);
+            break;
         case 68:
-            return gdb_get_regl(mem_buf, env->ctr);
+            gdb_get_regl(mem_buf, env->ctr);
+            break;
         case 69:
-            return gdb_get_regl(mem_buf, env->xer);
+            gdb_get_regl(mem_buf, env->xer);
+            break;
         case 70:
-            {
-                if (gdb_has_xml) {
-                    return 0;
-                }
-                return gdb_get_reg32(mem_buf, env->fpscr);
-            }
+            gdb_get_reg32(mem_buf, env->fpscr);
+            break;
         }
     }
-    return 0;
+    return r;
 }
 
 int ppc_cpu_gdb_write_register(CPUState *cs, uint8_t *mem_buf, int n)
 {
     PowerPCCPU *cpu = POWERPC_CPU(cs);
     CPUPPCState *env = &cpu->env;
+    int r = ppc_gdb_register_len(n);
 
+    if (!r) {
+        return r;
+    }
     if (n < 32) {
         /* gprs */
         env->gpr[n] = ldtul_p(mem_buf);
-        return sizeof(target_ulong);
     } else if (n < 64) {
         /* fprs */
-        if (gdb_has_xml) {
-            return 0;
-        }
         env->fpr[n-32] = ldfq_p(mem_buf);
-        return 8;
     } else {
         switch (n) {
         case 64:
             env->nip = ldtul_p(mem_buf);
-            return sizeof(target_ulong);
+            break;
         case 65:
             ppc_store_msr(env, ldtul_p(mem_buf));
-            return sizeof(target_ulong);
+            break;
         case 66:
             {
                 uint32_t cr = ldl_p(mem_buf);
                 int i;
                 for (i = 0; i < 8; i++) {
                     env->crf[i] = (cr >> (32 - ((i + 1) * 4))) & 0xF;
                 }
-                return 4;
+                break;
             }
         case 67:
             env->lr = ldtul_p(mem_buf);
-            return sizeof(target_ulong);
+            break;
         case 68:
             env->ctr = ldtul_p(mem_buf);
-            return sizeof(target_ulong);
+            break;
         case 69:
             env->xer = ldtul_p(mem_buf);
-            return sizeof(target_ulong);
+            break;
         case 70:
             /* fpscr */
-            if (gdb_has_xml) {
-                return 0;
-            }
             store_fpscr(env, ldtul_p(mem_buf), 0xffffffff);
-            return sizeof(target_ulong);
+            break;
         }
     }
-    return 0;
+    return r;
 }