2 files changed, 232 insertions, 0 deletions
diff --git a/src/cache/simt_cache.c b/src/cache/simt_cache.c
new file mode 100644
index 0000000..327746d
--- /dev/null
+++ b/src/cache/simt_cache.c
@@ -0,0 +1,231 @@
+#include <gran/cache/simt_cache.h>
+
+#define VEC_NAME lanes
+#define VEC_TYPE struct component *
+#include <conts/vec.h>
+
+struct req {
+	struct reg reg;
+	bool queued;
+};
+
+#define VEC_NAME reqs
+#define VEC_TYPE struct req
+#include <conts/vec.h>
+
+struct simt_cache {
+	struct component component;
+	struct component *mem;
+	struct lanes lanes;
+	struct reqs reqs;
+	uint64_t rcv;
+	uint32_t rr;
+};
+
+static stat simt_cache_ext_send(struct simt_cache *cache, size_t i, struct req *r)
+{
+	assert(r->reg.busy);
+
+	/* do fixups for sending */
+	struct packet p = r->reg.pkt;
+	if (is_set(&p, PACKET_READ))
+		p.mask = ~0ULL;
+
+	p.from = cache->rcv | i;
+	return SEND(&cache->component, cache->mem, p);
+}
+
+static stat simt_cache_clock(struct simt_cache *cache)
+{
+	struct req *shared = reqs_at(&cache->reqs, cache->rr);
+
+	/* start sending out queued stuff */
+	for (size_t i = 0; i < reqs_len(&cache->reqs); ++i) {
+		struct req *r = reqs_at(&cache->reqs, i);
+		if (!r->queued)
+			continue;
+
+		if (!r->reg.busy)
+			continue;
+
+		struct packet *p = &r->reg.pkt;
+
+		/* if we're trying to read from the same address as the shared reg and
+		 * we're not currently in charge of the shared reg, we can stop queuing
+		 * as shared reg will take care of our request as well */
+		if (shared->reg.busy
+				&& is_set(&shared->reg.pkt, PACKET_READ)
+				&& is_set(p, PACKET_READ)
+				&& p->to == shared->reg.pkt.to
+				&& i != cache->rr) {
+			r->queued = false;
+			continue;
+		}
+
+		size_t block_idx = (p->to / 64) % reqs_len(&cache->reqs);
+
+		/* check if the address in this packet can be directly sent to
+		 * the corresponding block port, i.e. the 64 byte block matches
+		 * our index. Alternatively, if we're currently holding the
+		 * shared register, we can send to any block index */
+		if (block_idx == i || cache->rr == i) {
+			stat ok = simt_cache_ext_send(cache, i, r);
+			if (ok == OK) {
+				r->queued = false;
+				continue;
+			}
+
+			if (ok == EBUSY)
+				continue;
+
+			/* something went wrong */
+			return ok;
+		}
+	}
+
+	/* if we're not waiting on a shared request, move forward to next active
+	 * element to prevent deadlocks */
+	if (!shared->reg.busy)
+	for (size_t i = 0; i < reqs_len(&cache->reqs); ++i) {
+		cache->rr = (cache->rr + 1) % reqs_len(&cache->reqs);
+		if (reqs_at(&cache->reqs, cache->rr)->reg.busy)
+			break;
+	}
+
+	return OK;
+}
+
+static stat simt_cache_broadcast(struct simt_cache *cache, struct packet pkt)
+{
+	assert(is_set(&pkt, PACKET_READ));
+	for (size_t i = 0; i < reqs_len(&cache->reqs); ++i) {
+		struct req *r = reqs_at(&cache->reqs, i);
+		if (!r->reg.busy)
+			continue;
+
+		if (r->reg.pkt.to != pkt.from)
+			continue;
+
+		if (!is_set(&r->reg.pkt, PACKET_READ))
+			continue;
+
+		struct component *lane = *lanes_at(&cache->lanes, i);
+
+		pkt.mask = r->reg.pkt.mask;
+		pkt.to   = r->reg.pkt.from;
+
+		stat ok = SEND(&cache->component, lane, pkt);
+
+		/* no reason for core to be blocked */
+		assert(ok == OK);
+
+		r->reg.busy = false;
+
+		/* queued might be set at this point if there was an attempt to
+		 * send a packet that failed, but we can deal with it here */
+		r->queued   = false;
+	}
+
+	return OK;
+}
+
+static stat simt_cache_handle_response(struct simt_cache *cache, struct packet pkt)
+{
+	/** @todo handle external requests, this currently only accepts
+	 * responses and an IPI would not work with this */
+	assert(!is_set(&pkt, PACKET_ERROR));
+	assert(is_set(&pkt, PACKET_DONE));
+	assert(is_set(&pkt, PACKET_READ) ? pkt.mask == ~0ULL : 1);
+
+	uint32_t idx = (uint32_t)pkt.to;
+	if (cache->rr == idx) {
+		/* round robin satisfied, move to next element */
+		cache->rr = (cache->rr + 1) % reqs_len(&cache->reqs);
+		if (is_set(&pkt, PACKET_READ))
+			return simt_cache_broadcast(cache, pkt);
+	}
+
+	struct req *r = reqs_at(&cache->reqs, idx);
+	assert(!r->queued);
+	assert(r->reg.busy);
+	assert(r->reg.pkt.to == pkt.from);
+
+	/* restore rewritten fields */
+	pkt.mask = r->reg.pkt.mask;
+	pkt.to   = r->reg.pkt.from;
+
+	r->reg.busy = false;
+
+	struct component *lane = *lanes_at(&cache->lanes, idx);
+	stat ok = SEND(&cache->component, lane, pkt);
+	assert(ok == OK);
+	return ok;
+}
+
+static stat simt_cache_receive(struct simt_cache *cache,
+		struct component *from, struct packet pkt)
+{
+	if (cache->mem == from)
+		return simt_cache_handle_response(cache, pkt);
+
+	uint32_t idx = pkt.from >> 32;
+	struct component *lane = *lanes_at(&cache->lanes, idx);
+	if (lane != from)
+		return ENOSUCH;
+
+	struct req *r = reqs_at(&cache->reqs, idx);
+	if (r->reg.busy)
+		return EBUSY;
+
+	assert(r->queued == false);
+	r->reg.busy = true;
+	r->reg.pkt = pkt;
+	r->queued = true;
+
+	return OK;
+}
+
+static void simt_cache_destroy(struct simt_cache *cache)
+{
+	lanes_destroy(&cache->lanes);
+	reqs_destroy(&cache->reqs);
+	free(cache);
+}
+
+struct component *create_simt_cache(uint64_t rcv, size_t num_lanes, struct component *mem)
+{
+	struct simt_cache *cache = calloc(1, sizeof(struct simt_cache));
+	if (!cache)
+		return NULL;
+
+	cache->component.clock = (clock_callback)simt_cache_clock;
+	cache->component.receive = (receive_callback)simt_cache_receive;
+	cache->component.destroy = (destroy_callback)simt_cache_destroy;
+
+	cache->lanes = lanes_create(num_lanes);
+	cache->reqs  = reqs_create(num_lanes);
+	cache->mem   = mem;
+	cache->rcv   = rcv;
+	cache->rr    = 0;
+
+	struct req empty = {
+		.reg = {
+			.pkt = {},
+			.busy = false
+		},
+		.queued = false
+	};
+
+	for (size_t i = 0; i < num_lanes; ++i) {
+		reqs_append(&cache->reqs, empty);
+		lanes_append(&cache->lanes, NULL);
+	}
+
+	return &cache->component;
+}
+
+void simt_cache_connect_lane(struct component *c, size_t i, struct component *e)
+{
+	struct simt_cache *cache = (struct simt_cache *)c;
+	*lanes_at(&cache->lanes, i) = e;
+}
diff --git a/src/cache/source.mk b/src/cache/source.mk
new file mode 100644
index 0000000..20f0bf9
--- /dev/null
+++ b/src/cache/source.mk
@@ -0,0 +1 @@
+GRAN_SOURCES += src/cache/simt_cache.c