Add a scatter-gather list type and accessors (Avi Kivity)

Scatter-gather lists are used extensively in dma-capable devices; a
single data structure allows more code reuse later on.

Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6522 c046a42c-6fe2-441c-8c8c-71466251a162

Makefile.target

@@ -500,7 +500,7 @@ endif #CONFIG_BSD_USER
 # System emulator target
 ifndef CONFIG_USER_ONLY
 
-OBJS=vl.o osdep.o monitor.o pci.o loader.o isa_mmio.o machine.o
+OBJS=vl.o osdep.o monitor.o pci.o loader.o isa_mmio.o machine.o dma-helpers.o
 # virtio has to be here due to weird dependency between PCI and virtio-net.
 # need to fix this properly
 OBJS+=virtio.o virtio-blk.o virtio-balloon.o virtio-net.o virtio-console.o

dma-helpers.c

@@ -0,0 +1,38 @@
+/*
+ * DMA helper functions
+ *
+ * Copyright (c) 2009 Red Hat
+ *
+ * This work is licensed under the terms of the GNU General Public License
+ * (GNU GPL), version 2 or later.
+ */
+
+#include "dma.h"
+
+
+void qemu_sglist_init(QEMUSGList *qsg, int alloc_hint)
+{
+    qsg->sg = qemu_malloc(alloc_hint * sizeof(ScatterGatherEntry));
+    qsg->nsg = 0;
+    qsg->nalloc = alloc_hint;
+    qsg->size = 0;
+}
+
+void qemu_sglist_add(QEMUSGList *qsg, target_phys_addr_t base,
+                     target_phys_addr_t len)
+{
+    if (qsg->nsg == qsg->nalloc) {
+        qsg->nalloc = 2 * qsg->nalloc + 1;
+        qsg->sg = qemu_realloc(qsg->sg, qsg->nalloc * sizeof(ScatterGatherEntry));
+    }
+    qsg->sg[qsg->nsg].base = base;
+    qsg->sg[qsg->nsg].len = len;
+    qsg->size += len;
+    ++qsg->nsg;
+}
+
+void qemu_sglist_destroy(QEMUSGList *qsg)
+{
+    qemu_free(qsg->sg);
+}
+

dma.h

@@ -0,0 +1,33 @@
+/*
+ * DMA helper functions
+ *
+ * Copyright (c) 2009 Red Hat
+ *
+ * This work is licensed under the terms of the GNU General Public License
+ * (GNU GPL), version 2 or later.
+ */
+
+#ifndef DMA_H
+#define DMA_H
+
+#include <stdio.h>
+#include "cpu.h"
+
+typedef struct {
+    target_phys_addr_t base;
+    target_phys_addr_t len;
+} ScatterGatherEntry;
+
+typedef struct {
+    ScatterGatherEntry *sg;
+    int nsg;
+    int nalloc;
+    target_phys_addr_t size;
+} QEMUSGList;
+
+void qemu_sglist_init(QEMUSGList *qsg, int alloc_hint);
+void qemu_sglist_add(QEMUSGList *qsg, target_phys_addr_t base,
+                     target_phys_addr_t len);
+void qemu_sglist_destroy(QEMUSGList *qsg);
+
+#endif