gwj / at91sam9263 · Commits

Commit ec2db7de7a280ce8d943e1a14463609d44b2b3e8

Authored by pbrook
1 parent 417f38f0

ARM timer counts down, not up. 


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@2214 c046a42c-6fe2-441c-8c8c-71466251a162
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Showing 1 changed file with 5 additions and 5 deletions
hw/arm_timer.c
  View file @ec2db7d
... ... @@ -107,29 +107,29 @@ static void arm_timer_update(arm_timer_state *s, int64_t now)
107 107 /* Return the current value of the timer. */
108 108 static uint32_t arm_timer_getcount(arm_timer_state *s, int64_t now)
109 109 {
110   - int64_t elapsed;
  110 + int64_t left;
111 111 int64_t period;
112 112  
113 113 if (s->count == 0)
114 114 return 0;
115 115 if ((s->control & TIMER_CTRL_ENABLE) == 0)
116 116 return s->count;
117   - elapsed = now - s->loaded;
  117 + left = s->expires - now;
118 118 period = s->expires - s->loaded;
119 119 /* If the timer should have expired then return 0. This can happen
120 120 when the host timer signal doesnt occur immediately. It's better to
121 121 have a timer appear to sit at zero for a while than have it wrap
122 122 around before the guest interrupt is raised. */
123 123 /* ??? Could we trigger the interrupt here? */
124   - if (elapsed > period)
  124 + if (left < 0)
125 125 return 0;
126 126 /* We need to calculate count * elapsed / period without overfowing.
127 127 Scale both elapsed and period so they fit in a 32-bit int. */
128 128 while (period != (int32_t)period) {
129 129 period >>= 1;
130   - elapsed >>= 1;
  130 + left >>= 1;
131 131 }
132   - return ((uint64_t)s->count * (uint64_t)(int32_t)elapsed)
  132 + return ((uint64_t)s->count * (uint64_t)(int32_t)left)
133 133 / (int32_t)period;
134 134 }
135 135  
... ...