technically speaking deadlock free, but starves

1 files changed, 78 insertions, 0 deletions

diff --git a/src/mem/simple_mem.c b/src/mem/simple_mem.c
new file mode 100644
index 0000000..0a3a3ce
--- /dev/null
+++ b/src/mem/simple_mem.c
@@ -0,0 +1,78 @@
+/* SPDX-License-Identifier: copyleft-next-0.3.1 */
+/* Copyright 2023 Kim Kuparinen < kimi.h.kuparinen@gmail.com > */
+
+#include <string.h>
+#include <stdlib.h>
+#include <stdbool.h>
+
+#include <gran/mem/simple_mem.h>
+
+struct simple_mem {
+	struct component component;
+	struct component *send;
+	struct packet pkt;
+	bool busy;
+
+	size_t size;
+	uint8_t buf[];
+};
+
+static stat simple_mem_clock(struct simple_mem *mem)
+{
+	if (!mem->busy)
+		return OK;
+
+	stat r = SEND(mem, mem->send, mem->pkt);
+	if (r == EBUSY)
+		return OK;
+
+	mem->busy = false;
+	return OK;
+}
+
+static stat simple_mem_receive(struct simple_mem *mem, struct component *from, struct packet pkt)
+{
+	if (mem->busy)
+		return EBUSY;
+
+	mem->busy = true;
+	mem->send = from;
+
+	uint64_t offset = pkt.to % mem->size;
+	if (offset >= mem->size) {
+		error("read outside memory");
+		mem->pkt = response(pkt);
+		set_flags(&mem->pkt, PACKET_ERROR);
+		return OK;
+	}
+
+	if (is_set(&pkt, PACKET_READ))
+		checked_copyto(&pkt, mem->buf + offset);
+	else if (is_set(&pkt, PACKET_WRITE))
+		checked_copyfrom(&pkt, mem->buf + offset);
+	else
+		abort();
+
+	mem->pkt = response(pkt);
+	set_flags(&mem->pkt, PACKET_DONE);
+	return OK;
+}
+
+struct component *create_simple_mem(size_t size)
+{
+	struct simple_mem *new = calloc(1, sizeof(struct simple_mem) + size);
+	if (!new)
+		return NULL;
+
+	new->size = size;
+	new->component.receive = (receive_callback)simple_mem_receive;
+	new->component.clock = (clock_callback)simple_mem_clock;
+	return (struct component *)new;
+}
+
+void init_simple_mem(struct component *m, uintptr_t addr, size_t size,
+                     void *data)
+{
+	struct simple_mem *mem = (struct simple_mem *)m;
+	memcpy(mem->buf + addr, data, size);
+}