technically speaking deadlock free, but starves

2 files changed, 146 insertions, 0 deletions

diff --git a/src/grid/node.c b/src/grid/node.c
new file mode 100644
index 0000000..16cce1b
--- /dev/null
+++ b/src/grid/node.c
@@ -0,0 +1,145 @@
+/* very simple grid node with 32bit private region, does not currently signal
+ * being busy or anything. I think I might have to refine the message passing
+ * interface I have, but this is good enough.
+ *
+ * Each node should have a router beneath it, just to simplify my life. A router
+ * is basically a bus with a fallback ascension path.
+ */
+#include <stdbool.h>
+
+#include <gran/grid/node.h>
+
+struct port {
+	struct component *send;
+	struct packet pkt;
+	bool busy;
+};
+
+struct grid_node {
+	struct component component;
+	uint16_t x, y;
+
+	struct port left, right, up, down, lower;
+};
+
+static void port_clock(struct grid_node *grid, struct port *port)
+{
+	if (!port->busy)
+		return;
+
+	stat r = SEND(grid, port->send, port->pkt);
+	if (r == EBUSY)
+		return;
+
+	port->busy = false;
+}
+
+static stat grid_clock(struct grid_node *grid)
+{
+	port_clock(grid, &grid->left);
+	port_clock(grid, &grid->right);
+	port_clock(grid, &grid->up);
+	port_clock(grid, &grid->down);
+	port_clock(grid, &grid->lower);
+	return OK;
+}
+
+static stat port_receive(struct port *port, struct packet pkt)
+{
+	if (port->busy)
+		return EBUSY;
+
+	port->pkt = pkt;
+	port->busy = true;
+	return OK;
+}
+
+static stat grid_receive(struct grid_node *grid, struct component *from, struct packet pkt)
+{
+	uint16_t x;
+	uint16_t y;
+	uint64_t addr = pkt.to;
+	addr_grid(addr, NULL, &x, &y);
+
+	if (grid->x == x && grid->y == y) {
+		if (!grid->lower.send)
+			goto nosuch;
+
+		return port_receive(&grid->lower, pkt);
+	}
+
+	if (y < grid->y) {
+		if (!grid->down.send)
+			goto nosuch;
+
+		return port_receive(&grid->down, pkt);
+	}
+
+	if (y > grid->y) {
+		if (!grid->up.send)
+			goto nosuch;
+
+		return port_receive(&grid->up, pkt);
+	}
+
+	if (x < grid->x) {
+		if (!grid->left.send)
+			goto nosuch;
+
+		return port_receive(&grid->left, pkt);
+	}
+
+	if (x > grid->x) {
+		if (!grid->right.send)
+			goto nosuch;
+
+		return port_receive(&grid->right, pkt);
+	}
+
+nosuch:
+	set_flags(&pkt, PACKET_ERROR);
+	if (from == grid->lower.send)
+		return port_receive(&grid->lower, pkt);
+
+	if (from == grid->left.send)
+		return port_receive(&grid->left, pkt);
+
+	if (from == grid->right.send)
+		return port_receive(&grid->right, pkt);
+
+	if (from == grid->down.send)
+		return port_receive(&grid->down, pkt);
+
+	if (from == grid->up.send)
+		return port_receive(&grid->up, pkt);
+
+	abort();
+	return OK;
+}
+
+struct component *create_grid_node(uint16_t x, uint16_t y)
+{
+	struct grid_node *node = calloc(1, sizeof(struct grid_node));
+	if (!node)
+		return NULL;
+
+	node->component.receive = (receive_callback)grid_receive;
+	node->component.clock = (clock_callback)grid_clock;
+	node->x = x;
+	node->y = y;
+	return (struct component *)node;
+}
+
+stat grid_node_connect(struct component *node,
+		struct component *left, struct component *right,
+		struct component *up, struct component *down,
+		struct component *lower)
+{
+	struct grid_node *n = (struct grid_node *)node;
+	n->left.send = left;
+	n->right.send = right;
+	n->up.send = up;
+	n->down.send = down;
+	n->lower.send = lower;
+	return OK;
+}
diff --git a/src/grid/source.mk b/src/grid/source.mk
new file mode 100644
index 0000000..e23d7db
--- /dev/null
+++ b/src/grid/source.mk
@@ -0,0 +1 @@
+SOURCES += src/grid/node.c