From 45f27b98cc9eaf87bdd6755e182ce5c25ff9e5d6 Mon Sep 17 00:00:00 2001
From: Douglas Clowes <dcl@ansto.gov.au>
Date: Thu, 19 Jul 2012 14:55:45 +1000
Subject: [PATCH] Minor improvement in timing and jitter of simulation r3654 |
 dcl | 2012-07-19 14:55:45 +1000 (Thu, 19 Jul 2012) | 1 line

---
 site_ansto/hardsup/Monitor/hware.c | 75 ++++++++++++++++++------------
 1 file changed, 46 insertions(+), 29 deletions(-)

diff --git a/site_ansto/hardsup/Monitor/hware.c b/site_ansto/hardsup/Monitor/hware.c
index 13819519..2ad84e0f 100644
--- a/site_ansto/hardsup/Monitor/hware.c
+++ b/site_ansto/hardsup/Monitor/hware.c
@@ -895,9 +895,12 @@ typedef struct device_private_t
 {
   /** extended 64-bit counter value */
   unsigned long long count64;
-  /* TODO time and count */
-  int source; /* count rate to be simulated */
-  struct timeval last_time;
+  /** count rate to be simulated */
+  int source;
+  /** time that count64 was last updated */
+  struct timeval prev_time;
+  /** time of most recent read operation */
+  struct timeval curr_time;
 } DEVICE_PRIVATE;
 
 int hware_ctor(const char* device_name, pHWARE* ptr)
@@ -908,56 +911,70 @@ int hware_ctor(const char* device_name, pHWARE* ptr)
   *ptr = hware;
   memset(hware, 0, sizeof(DEVICE_PRIVATE));
 
-  /* TODO time and count */
+  /* set initital conditions */
   hware->source = 1000; /* initial count rate */
-  gettimeofday(&hware->last_time, NULL);
-#if 0 /* DEBUG */
-  printf("hware_ctor: %s at %p\n", device_name, *ptr);
-#endif
+  hware->count64 = 0; /* initial counter value */
+  gettimeofday(&hware->curr_time, NULL); /* current time */
+  hware->prev_time = hware->curr_time; /* update time */
   return 0;
 }
 
 int hware_read(pHWARE hware, unsigned long long* value)
 {
-  struct timeval this_time;
   double delta_time;
-  long long delta_count = 0;
-  /* TODO time and count */
-  gettimeofday(&this_time, NULL);
-  delta_time = (this_time.tv_sec + 1e-6 * this_time.tv_usec) -
-    (hware->last_time.tv_sec + 1e-6 * hware->last_time.tv_usec);
-  delta_count = (long long)(0.5 + 1000 * delta_time * hware->source);
-  hware->count64 += delta_count;
-  hware->last_time = this_time;
-  *value = hware->count64 / 1000;
+  unsigned long long delta_count = 0;
+  unsigned long long total_count = 0;
+  /* calculate time since count64 update in microseconds */
+  gettimeofday(&hware->curr_time, NULL);
+  delta_time = (hware->curr_time.tv_sec + 1e-6 * hware->curr_time.tv_usec) -
+    (hware->prev_time.tv_sec + 1e-6 * hware->prev_time.tv_usec);
+  /* calculate counts since then */
+  delta_count = (long long)(0.5 + delta_time * hware->source);
+  /* calculate the new total counts */
+  total_count = hware->count64 + delta_count;
+  /* periodically update count64 */
+  if (delta_time > 60) {
+    hware->count64 = total_count;
+    hware->prev_time = hware->curr_time;
+  }
+  /* return the total count */
+  *value = total_count;
   return 0;
 }
+/*
+ * Change the count rate
+ */
 int hware_source(pHWARE hware, int value)
 {
-#if 0 /* DEBUG */
-  int old_source = hware->source;
-#endif
+  /* calculate the new count rate */
+  int new_source;
   switch (value)
   {
     case 0:
-      hware->source = 10000;
+      new_source = 10000;
       break;
     case 1:
-      hware->source = 20000000;
+      new_source = 20000000;
       break;
     case 2:
-      hware->source = 100000;
+      new_source = 100000;
       break;
     case 3:
-      hware->source = 80000000;
+      new_source = 80000000;
       break;
     default:
-      hware->source = value;
+      new_source = abs(value);
       break;
   }
-#if 0 /* DEBUG */
-  printf("hware_source: %d moves %d to %d at %p\n", value, old_source, hware->source, hware);
-#endif
+  /* only do this if it has changed */
+  if (new_source != hware->source) {
+    /* save the current count where the slope changes */
+    hware_read(hware, &hware->count64);
+    /* save the current time where the slope changes */
+    hware->prev_time = hware->curr_time;
+    /* save the new slope */
+    hware->source = new_source;
+  }
   return 0;
 }
 int hware_filter(pHWARE hware, int value)