[Qemu-devel] [4190] Optimize MIPS timer read/write functions

[Aurelien Jarno]

Revision: 4190
          http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=4190
Author:   aurel32
Date:     2008-04-11 04:55:31 +0000 (Fri, 11 Apr 2008)

Log Message:
-----------
Optimize MIPS timer read/write functions

Modified Paths:
--------------
    trunk/hw/mips_timer.c

Modified: trunk/hw/mips_timer.c
===================================================================
--- trunk/hw/mips_timer.c       2008-04-11 04:55:24 UTC (rev 4189)
+++ trunk/hw/mips_timer.c       2008-04-11 04:55:31 UTC (rev 4190)
@@ -2,6 +2,8 @@
 #include "mips.h"
 #include "qemu-timer.h"
 
+#define TIMER_FREQ     100 * 1000 * 1000
+
 void cpu_mips_irqctrl_init (void)
 {
 }
@@ -24,49 +26,41 @@
     else
         return env->CP0_Count +
             (uint32_t)muldiv64(qemu_get_clock(vm_clock),
-                               100 * 1000 * 1000, ticks_per_sec);
+                               TIMER_FREQ, ticks_per_sec);
 }
 
-void cpu_mips_store_count (CPUState *env, uint32_t count)
+static void cpu_mips_timer_update(CPUState *env)
 {
     uint64_t now, next;
-    uint32_t tmp;
-    uint32_t compare = env->CP0_Compare;
+    uint32_t wait;
 
-    tmp = count;
-    if (count == compare)
-        tmp++;
     now = qemu_get_clock(vm_clock);
-    next = now + muldiv64(compare - tmp, ticks_per_sec, 100 * 1000 * 1000);
-    if (next == now)
-       next++;
-#if 0
-    if (logfile) {
-        fprintf(logfile, "%s: 0x%08" PRIx64 " %08x %08x => 0x%08" PRIx64 "\n",
-                __func__, now, count, compare, next - now);
-    }
-#endif
-    /* Store new count and compare registers */
-    env->CP0_Compare = compare;
-    env->CP0_Count =
-        count - (uint32_t)muldiv64(now, 100 * 1000 * 1000, ticks_per_sec);
-    /* Adjust timer */
+    wait = env->CP0_Compare - env->CP0_Count -
+           (uint32_t)muldiv64(now, TIMER_FREQ, ticks_per_sec);
+    next = now + muldiv64(wait, ticks_per_sec, TIMER_FREQ);
     qemu_mod_timer(env->timer, next);
 }
 
-static void cpu_mips_update_count (CPUState *env, uint32_t count)
+void cpu_mips_store_count (CPUState *env, uint32_t count)
 {
     if (env->CP0_Cause & (1 << CP0Ca_DC))
-        return;
-
-    cpu_mips_store_count(env, count);
+        env->CP0_Count = count;
+    else {
+        /* Store new count register */
+        env->CP0_Count =
+            count - (uint32_t)muldiv64(qemu_get_clock(vm_clock),
+                                       TIMER_FREQ, ticks_per_sec);
+        /* Update timer timer */
+        cpu_mips_timer_update(env);
+    }
 }
 
 void cpu_mips_store_compare (CPUState *env, uint32_t value)
 {
     env->CP0_Compare = value;
-    cpu_mips_update_count(env, cpu_mips_get_count(env));
-    if ((env->CP0_Config0 & (0x7 << CP0C0_AR)) == (1 << CP0C0_AR))
+    if (!(env->CP0_Cause & (1 << CP0Ca_DC)))
+        cpu_mips_timer_update(env);
+    if (env->insn_flags & ISA_MIPS32R2)
         env->CP0_Cause &= ~(1 << CP0Ca_TI);
     qemu_irq_lower(env->irq[(env->CP0_IntCtl >> CP0IntCtl_IPTI) & 0x7]);
 }
@@ -80,7 +74,7 @@
 {
     /* Store the current value */
     env->CP0_Count += (uint32_t)muldiv64(qemu_get_clock(vm_clock),
-                                         100 * 1000 * 1000, ticks_per_sec);
+                                         TIMER_FREQ, ticks_per_sec);
 }
 
 static void mips_timer_cb (void *opaque)
@@ -97,8 +91,8 @@
     if (env->CP0_Cause & (1 << CP0Ca_DC))
         return;
 
-    cpu_mips_update_count(env, cpu_mips_get_count(env));
-    if ((env->CP0_Config0 & (0x7 << CP0C0_AR)) == (1 << CP0C0_AR))
+    cpu_mips_timer_update(env);
+    if (env->insn_flags & ISA_MIPS32R2)
         env->CP0_Cause |= 1 << CP0Ca_TI;
     qemu_irq_raise(env->irq[(env->CP0_IntCtl >> CP0IntCtl_IPTI) & 0x7]);
 }
@@ -107,5 +101,5 @@
 {
     env->timer = qemu_new_timer(vm_clock, &mips_timer_cb, env);
     env->CP0_Compare = 0;
-    cpu_mips_update_count(env, 1);
+    cpu_mips_store_count(env, 1);
 }