From 34d681a00a7fc3c8d82a5ba3082dd5524f2a8389 Mon Sep 17 00:00:00 2001
From: Chernov Dmitriy <cd_work@mail.ru>
Date: 周二, 01 3月 2016 21:26:22 +0800
Subject: [PATCH] The basic implementation completed. Tests are needed. (issue #73)

---
 libscpi/src/fifo.c |   83 +++++++++++++++++++++++++++++++----------
 1 files changed, 63 insertions(+), 20 deletions(-)

diff --git a/libscpi/src/fifo.c b/libscpi/src/fifo.c
index 341bc8e..6c125ff 100644
--- a/libscpi/src/fifo.c
+++ b/libscpi/src/fifo.c
@@ -5,10 +5,12 @@
  * Initialize fifo
  * @param fifo
  */
-void fifo_init(scpi_fifo_t * fifo) {
+void fifo_init(scpi_fifo_t * fifo, scpi_error_t * data, int16_t size) {
     fifo->wr = 0;
     fifo->rd = 0;
-    fifo->size = FIFO_SIZE;
+    fifo->count = 0;
+    fifo->data = data;
+    fifo->size = size;
 }
 
 /**
@@ -18,23 +20,44 @@
 void fifo_clear(scpi_fifo_t * fifo) {
     fifo->wr = 0;
     fifo->rd = 0;
+    fifo->count = 0;
 }
 
 /**
- * Add element to fifo. If fifo is full, remove last element.
+ * Test if fifo is empty
  * @param fifo
- * @param value
- * @return 
+ * @return
  */
-scpi_bool_t fifo_add(scpi_fifo_t * fifo, int16_t value) {
+scpi_bool_t fifo_is_empty(scpi_fifo_t * fifo) {
+    return fifo->count == 0;
+}
+
+/**
+ * Test if fifo is full
+ * @param fifo
+ * @return
+ */
+scpi_bool_t fifo_is_full(scpi_fifo_t * fifo) {
+    return fifo->count == fifo->size;
+}
+
+/**
+ * Add element to fifo. If fifo is full, return FALSE.
+ * @param fifo
+ * @param err
+ * @param info
+ * @return
+ */
+scpi_bool_t fifo_add(scpi_fifo_t * fifo, int16_t err, char * info) {
     /* FIFO full? */
-    if (fifo->wr == ((fifo->rd + fifo->size) % (fifo->size + 1))) {
-        fifo_remove(fifo, NULL);
+    if (fifo_is_full(fifo)) {
+        return FALSE;
     }
 
-    fifo->data[fifo->wr] = value;
-    fifo->wr = (fifo->wr + 1) % (fifo->size + 1);
-
+    fifo->data[fifo->wr].error_code = err;
+	fifo->data[fifo->wr].device_dependent_info = info;
+    fifo->wr = (fifo->wr + 1) % (fifo->size);
+    fifo->count += 1;
     return TRUE;
 }
 
@@ -44,17 +67,40 @@
  * @param value
  * @return FALSE - fifo is empty
  */
-scpi_bool_t fifo_remove(scpi_fifo_t * fifo, int16_t * value) {
+scpi_bool_t fifo_remove(scpi_fifo_t * fifo, scpi_error_t * value) {
     /* FIFO empty? */
-    if (fifo->wr == fifo->rd) {
+    if (fifo_is_empty(fifo)) {
         return FALSE;
     }
 
-    if(value) {
+    if (value) {
         *value = fifo->data[fifo->rd];
     }
 
-    fifo->rd = (fifo->rd + 1) % (fifo->size + 1);
+    fifo->rd = (fifo->rd + 1) % (fifo->size);
+    fifo->count -= 1;
+
+    return TRUE;
+}
+
+/**
+ * Remove last element from fifo
+ * @param fifo
+ * @param value
+ * @return FALSE - fifo is empty
+ */
+scpi_bool_t fifo_remove_last(scpi_fifo_t * fifo, scpi_error_t * value) {
+    /* FIFO empty? */
+    if (fifo_is_empty(fifo)) {
+        return FALSE;
+    }
+
+    fifo->wr = (fifo->wr + fifo->size - 1) % (fifo->size);
+
+    if (value) {
+        *value = fifo->data[fifo->wr];
+    }
+    fifo->count -= 1;
 
     return TRUE;
 }
@@ -63,12 +109,9 @@
  * Retrive number of elements in fifo
  * @param fifo
  * @param value
- * @return 
+ * @return
  */
 scpi_bool_t fifo_count(scpi_fifo_t * fifo, int16_t * value) {
-    *value = fifo->wr - fifo->rd;
-    if (*value < 0) {
-        *value += (fifo->size + 1);
-    }
+    *value = fifo->count;
     return TRUE;
 }

--
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