[Qemu-devel] [PATCH 07/14] hw: Added generic FIFO API.

[Peter Crosthwaite <peter.crosthwaite@petalogix.com>]

From: Peter A. G. Crosthwaite <peter.crosthwaite@petalogix.com>

Added a FIFO API that can be used to create and operate byte FIFOs.

Signed-off-by: Peter A. G. Crosthwaite <peter.crosthwaite@petalogix.com>
---
 hw/Makefile.objs |    1 +
 hw/fifo.c        |   78 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 hw/fifo.h        |   47 ++++++++++++++++++++++++++++++++
 3 files changed, 126 insertions(+), 0 deletions(-)
 create mode 100644 hw/fifo.c
 create mode 100644 hw/fifo.h

diff --git a/hw/Makefile.objs b/hw/Makefile.objs
index ecdbe44..e18ae34 100644
--- a/hw/Makefile.objs
+++ b/hw/Makefile.objs
@@ -15,6 +15,7 @@ hw-obj-$(CONFIG_ECC) += ecc.o
 hw-obj-$(CONFIG_NAND) += nand.o
 hw-obj-$(CONFIG_PFLASH_CFI01) += pflash_cfi01.o
 hw-obj-$(CONFIG_PFLASH_CFI02) += pflash_cfi02.o
+hw-obj-y += fifo.o
 
 hw-obj-$(CONFIG_M48T59) += m48t59.o
 hw-obj-$(CONFIG_ESCC) += escc.o
diff --git a/hw/fifo.c b/hw/fifo.c
new file mode 100644
index 0000000..366dae4
--- /dev/null
+++ b/hw/fifo.c
@@ -0,0 +1,78 @@
+/*
+ * Generic FIFO component, implemented as a circular buffer.
+ *
+ * Copyright (c) 2012 Peter A. G. Crosthwaite
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "fifo.h"
+
+void fifo8_create(Fifo8 *fifo, uint32_t capacity)
+{
+    fifo->data = g_new(uint8_t, capacity);
+    fifo->capacity = capacity;
+    fifo->head = 0;
+    fifo->num = 0;
+}
+
+void fifo8_destroy(Fifo8 *fifo)
+{
+    g_free(fifo->data);
+}
+
+void fifo8_push(Fifo8 *fifo, uint8_t data)
+{
+    if (fifo->num == fifo->capacity) {
+        abort();
+    }
+    fifo->data[(fifo->head + fifo->num) % fifo->capacity] = data;
+    fifo->num++;
+}
+
+uint8_t fifo8_pop(Fifo8 *fifo)
+{
+    uint8_t ret;
+
+    if (fifo->num == 0) {
+        abort();
+    }
+    ret = fifo->data[fifo->head++];
+    fifo->head %= fifo->capacity;
+    fifo->num--;
+    return ret;
+}
+
+void fifo8_reset(Fifo8 *fifo)
+{
+    fifo->num = 0;
+}
+
+bool fifo8_is_empty(Fifo8 *fifo)
+{
+    return (fifo->num == 0);
+}
+
+bool fifo8_is_full(Fifo8 *fifo)
+{
+    return (fifo->num == fifo->capacity);
+}
+
+const VMStateDescription vmstate_fifo8 = {
+    .name = "SSISlave",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .minimum_version_id_old = 1,
+    .fields      = (VMStateField[]) {
+        VMSTATE_VBUFFER_UINT32(data, Fifo8, 1, NULL, 0, capacity),
+        VMSTATE_UINT32(head, Fifo8),
+        VMSTATE_UINT32(num, Fifo8),
+        VMSTATE_END_OF_LIST()
+    }
+};
diff --git a/hw/fifo.h b/hw/fifo.h
new file mode 100644
index 0000000..3fb09ff
--- /dev/null
+++ b/hw/fifo.h
@@ -0,0 +1,47 @@
+#ifndef FIFO_H
+#define FIFO_H
+
+#include "hw.h"
+
+typedef struct {
+    /* All fields are private */
+    uint8_t *data;
+    uint32_t capacity;
+    uint32_t head;
+    uint32_t num;
+} Fifo8;
+
+/* create a fifo of the specified size */
+
+void fifo8_create(Fifo8 *, uint32_t);
+
+/* cleanup a fifo */
+
+void fifo8_destroy(Fifo8 *);
+
+/* push a data byte to the fifo. Behaviour is undefined if the fifo is full */
+
+void fifo8_push(Fifo8 *, uint8_t);
+
+/* pop a data byte from the fifo. Behviour is undefined if the fifo is empty */
+
+uint8_t fifo8_pop(Fifo8 *);
+
+/* reset (empty) the fifo */
+
+void fifo8_reset(Fifo8 *);
+
+bool fifo8_is_empty(Fifo8 *);
+bool fifo8_is_full(Fifo8 *);
+
+extern const VMStateDescription vmstate_fifo8;
+
+#define VMSTATE_FIFO8(_field, _state) {                              \
+    .name       = (stringify(_field)),                               \
+    .size       = sizeof(Fifo8),                                     \
+    .vmsd       = &vmstate_fifo8,                                    \
+    .flags      = VMS_STRUCT,                                        \
+    .offset     = vmstate_offset_value(_state, _field, Fifo8),       \
+}
+
+#endif /* FIFO_H */
-- 
1.7.0.4