From 9c88423d66e9b4eafecc658058f25f79e08ff120 Mon Sep 17 00:00:00 2001
From: Stephane D'Alu <sdalu@sdalu.com>
Date: Thu, 7 Jul 2016 20:41:09 +0200
Subject: move functions to hal_qei.*, fixed comments

---
 os/hal/src/hal_qei.c | 123 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 123 insertions(+)

(limited to 'os/hal/src')

diff --git a/os/hal/src/hal_qei.c b/os/hal/src/hal_qei.c
index a2b7303..abecdf8 100644
--- a/os/hal/src/hal_qei.c
+++ b/os/hal/src/hal_qei.c
@@ -46,6 +46,91 @@
 /* Driver exported functions.                                                */
 /*===========================================================================*/
 
+/**
+ * @brief   Helper for correclty handling overflow/underflow
+ *
+ * @details Underflow/overflow will be handled according to mode:
+ *          QEI_OVERFLOW_WRAP:    counter value will wrap around.
+ *          QEI_OVERFLOW_DISCARD: counter will not change
+ *          QEI_OVERFLOW_MINMAX:  counter will be updated upto min or max.
+ *
+ * @note    This function is for use by low level driver.
+ *
+ * @param[in,out] count counter value
+ * @param[in,out] delta adjustment value
+ * @param[in]     min   minimum allowed value for counter
+ * @param[in]     max   maximum allowed value for counter
+ * @param[in]     mode  how to handle overflow
+ *
+ * @return        true if counter underflow/overflow occured or
+ *                was due to occur
+ *
+ */
+bool qei_adjust_count(qeicnt_t *count, qeidelta_t *delta,
+		      qeicnt_t min, qeicnt_t max, qeioverflow_t mode) {
+  /* For information on signed integer overflow see:
+   * https://www.securecoding.cert.org/confluence/x/RgE
+   */
+
+  /* Get values */
+  const qeicnt_t   _count = *count;
+  const qeidelta_t _delta = *delta;
+
+  /* Overflow operation
+   */
+  if ((_delta > 0) && (_count > (max - _delta))) {
+    switch(mode) {
+    case QEI_OVERFLOW_WRAP:
+      *delta = 0;
+      *count = (min + (_count - (max - _delta))) - 1;
+      break;
+#if QEI_USE_OVERFLOW_DISCARD == TRUE
+    case QEI_OVERFLOW_DISCARD:
+      *delta = _delta;
+      *count = _count;
+      break;
+#endif
+#if QEI_USE_OVERFLOW_MINMAX == TRUE
+    case QEI_OVERFLOW_MINMAX:
+      *delta = _count - (max - _delta);
+      *count = max;
+      break;
+#endif
+    }
+    return true;
+    
+ /* Underflow operation
+  */
+  } else if ((_delta < 0) && (_count < (min - _delta))) {
+    switch(mode) {
+    case QEI_OVERFLOW_WRAP:
+      *delta = 0;
+      *count = (max + (_count - (min - _delta))) + 1;
+    break;
+#if QEI_USE_OVERFLOW_DISCARD == TRUE
+    case QEI_OVERFLOW_DISCARD:
+      *delta = _delta;
+      *count = _count;
+      break;
+#endif
+#if QEI_USE_OVERFLOW_MINMAX == TRUE
+    case QEI_OVERFLOW_MINMAX:
+      *delta = _count - (min - _delta);
+      *count = min;
+      break;
+#endif
+    }
+    return true;
+
+  /* Normal operation
+   */
+  } else {
+    *delta = 0;
+    *count = _count + _delta;
+    return false;
+  }
+}
+
 /**
  * @brief   QEI Driver initialization.
  * @note    This function is implicitly invoked by @p halInit(), there is
@@ -167,6 +252,44 @@ qeicnt_t qeiGetCount(QEIDriver *qeip) {
   return cnt;
 }
 
+/**
+ * @brief   Set counter value.
+ *
+ * @param[in] qeip      pointer to the @p QEIDriver object.
+ * @param[in] value     the new counter value.
+ *
+ * @api
+ */
+void qeiSetCount(QEIDriver *qeip, qeicnt_t value) {
+  osalDbgCheck(qeip != NULL);
+  osalDbgAssert((qeip->state == QEI_READY) || (qeip->state == QEI_ACTIVE),
+		"invalid state");
+
+  osalSysLock();
+  qei_lld_set_count(qeip, value);
+  osalSysUnlock();
+}
+
+/**
+ * @brief   Adjust the counter by delta.
+ *
+ * @param[in] qeip      pointer to the @p QEIDriver object.
+ * @param[in] delta     the adjustement value.
+ * @return              the remaining delta (can occur during overflow).
+ *
+ * @api
+ */
+qeidelta_t qeiAdjust(QEIDriver *qeip, qeidelta_t delta) {
+  osalDbgCheck(qeip != NULL);
+  osalDbgAssert((qeip->state == QEI_ACTIVE), "invalid state");
+
+  osalSysLock();
+  delta = qei_lld_adjust_count(qeip, delta);
+  osalSysUnlock();
+
+  return delta;
+}
+
 /**
  * @brief   Returns the counter delta from last reading.
  *
-- 
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