hw: Added generic FIFO API.

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

@@ -35,6 +35,7 @@ common-obj-$(CONFIG_APPLESMC) += applesmc.o
 common-obj-$(CONFIG_SMARTCARD) += ccid-card-passthru.o
 common-obj-$(CONFIG_SMARTCARD_NSS) += ccid-card-emulated.o
 common-obj-$(CONFIG_I8259) += i8259_common.o i8259.o
+common-obj-y += fifo.o
 
 # PPC devices
 common-obj-$(CONFIG_PREP_PCI) += prep_pci.o

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 = "Fifo8",
+    .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()
+    }
+};

hw/fifo.h

@@ -0,0 +1,99 @@
+#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;
+
+/**
+ * fifo8_create:
+ * @fifo: struct Fifo8 to initialise with new FIFO
+ * @capacity: capacity of the newly created FIFO
+ *
+ * Create a FIFO of the specified size. Clients should call fifo8_destroy()
+ * when finished using the fifo. The FIFO is initially empty.
+ */
+
+void fifo8_create(Fifo8 *fifo, uint32_t capacity);
+
+/**
+ * fifo8_destroy:
+ * @fifo: FIFO to cleanup
+ *
+ * Cleanup a FIFO created with fifo8_create(). Frees memory created for FIFO
+  *storage. The FIFO is no longer usable after this has been called.
+ */
+
+void fifo8_destroy(Fifo8 *fifo);
+
+/**
+ * fifo8_push:
+ * @fifo: FIFO to push to
+ * @data: data byte to push
+ *
+ * Push a data byte to the FIFO. Behaviour is undefined if the FIFO is full.
+ * Clients are responsible for checking for fullness using fifo8_is_full().
+ */
+
+void fifo8_push(Fifo8 *fifo, uint8_t data);
+
+/**
+ * fifo8_pop:
+ * @fifo: fifo to pop from
+ *
+ * Pop a data byte from the FIFO. Behaviour is undefined if the FIFO is empty.
+ * Clients are responsible for checking for emptyness using fifo8_is_empty().
+ *
+ * Returns: The popped data byte.
+ */
+
+uint8_t fifo8_pop(Fifo8 *fifo);
+
+/**
+ * fifo8_reset:
+ * @fifo: FIFO to reset
+ *
+ * Reset a FIFO. All data is discarded and the FIFO is emptied.
+ */
+
+void fifo8_reset(Fifo8 *fifo);
+
+/**
+ * fifo8_is_empty:
+ * @fifo: FIFO to check
+ *
+ * Check if a FIFO is empty.
+ *
+ * Returns: True if the fifo is empty, false otherwise.
+ */
+
+bool fifo8_is_empty(Fifo8 *fifo);
+
+/**
+ * fifo8_is_full:
+ * @fifo: FIFO to check
+ *
+ * Check if a FIFO is full.
+ *
+ * Returns: True if the fifo is full, false otherwise.
+ */
+
+bool fifo8_is_full(Fifo8 *fifo);
+
+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 */