1 files changed, 156 insertions, 0 deletions
diff --git a/utils/keytable/bpf_protocols/pulse_distance.c b/utils/keytable/bpf_protocols/pulse_distance.c
new file mode 100644
index 00000000..9e9ea4ad
--- /dev/null
+++ b/utils/keytable/bpf_protocols/pulse_distance.c
@@ -0,0 +1,156 @@
+// SPDX-License-Identifier: GPL-2.0+
+//
+// Copyright (C) 2018 Sean Young <sean@mess.org>
+
+#include <linux/lirc.h>
+#include <linux/bpf.h>
+
+#include "bpf_helpers.h"
+
+enum state {
+	STATE_INACTIVE,
+	STATE_HEADER_SPACE,
+	STATE_REPEAT_SPACE,
+	STATE_BITS_SPACE,
+	STATE_BITS_PULSE,
+	STATE_TRAILER,
+};
+
+struct decoder_state {
+	unsigned long bits;
+	enum state state;
+	unsigned int count;
+};
+
+struct bpf_map_def SEC("maps") decoder_state_map = {
+	.type = BPF_MAP_TYPE_ARRAY,
+	.key_size = sizeof(unsigned int),
+	.value_size = sizeof(struct decoder_state),
+	.max_entries = 1,
+};
+
+// These values can be overridden in the rc_keymap toml
+//
+// We abuse elf relocations. We cast the address of these variables to
+// an int, so that the compiler emits a mov immediate for the address
+// but uses it as an int. The bpf loader replaces the relocation with the
+// actual value (either overridden or taken from the data segment).
+int margin = 200;
+int header_pulse = 2125;
+int header_space = 1875;
+int repeat_pulse = 0;
+int repeat_space = 0;
+int bit_pulse = 625;
+int bit_0_space = 375;
+int bit_1_space = 1625;
+int trailer_pulse = 625;
+int bits = 4;
+int reverse = 0;
+int header_optional = 0;
+int rc_protocol = 64;
+
+#define BPF_PARAM(x) (int)(&(x))
+
+static inline int eq_margin(unsigned d1, unsigned d2)
+{
+	return ((d1 > (d2 - BPF_PARAM(margin))) && (d1 < (d2 + BPF_PARAM(margin))));
+}
+
+SEC("pulse_distance")
+int bpf_decoder(unsigned int *sample)
+{
+	unsigned int key = 0;
+	struct decoder_state *s = bpf_map_lookup_elem(&decoder_state_map, &key);
+
+	if (!s)
+		return 0;
+
+	switch (*sample & LIRC_MODE2_MASK) {
+	case LIRC_MODE2_SPACE:
+	case LIRC_MODE2_PULSE:
+	case LIRC_MODE2_TIMEOUT:
+		break;
+	default:
+		// not a timing events
+		return 0;
+	}
+
+	int duration = LIRC_VALUE(*sample);
+	int pulse = LIRC_IS_PULSE(*sample);
+
+	switch (s->state) {
+	case STATE_HEADER_SPACE:
+		if (!pulse && eq_margin(BPF_PARAM(header_space), duration))
+			s->state = STATE_BITS_PULSE;
+		else
+			s->state = STATE_INACTIVE;
+		break;
+	case STATE_REPEAT_SPACE:
+		if (!pulse && eq_margin(BPF_PARAM(repeat_space), duration))
+			s->state = STATE_TRAILER;
+		else
+			s->state = STATE_INACTIVE;
+		break;
+	case STATE_INACTIVE:
+		if (pulse && eq_margin(BPF_PARAM(header_pulse), duration)) {
+			s->bits = 0;
+			s->state = STATE_HEADER_SPACE;
+			s->count = 0;
+			break;
+		}
+		if (pulse && BPF_PARAM(repeat_pulse) > 0 &&
+		    eq_margin(BPF_PARAM(repeat_pulse), duration)) {
+			s->state = STATE_REPEAT_SPACE;
+			s->count = 0;
+			break;
+		}
+		if (!BPF_PARAM(header_optional))
+			break;
+		/* pass through */
+	case STATE_BITS_PULSE:
+		if (pulse && eq_margin(BPF_PARAM(bit_pulse), duration))
+			s->state = STATE_BITS_SPACE;
+		else
+			s->state = STATE_INACTIVE;
+		break;
+	case STATE_BITS_SPACE:
+		if (pulse) {
+			s->state = STATE_INACTIVE;
+			break;
+		}
+
+		unsigned long set_bit = 1;
+
+		if (BPF_PARAM(reverse))
+			set_bit <<= s->count;
+		else
+			s->bits <<= 1;
+
+		if (eq_margin(BPF_PARAM(bit_1_space), duration))
+			s->bits |= set_bit;
+		else if (!eq_margin(BPF_PARAM(bit_0_space), duration)) {
+			s->state = STATE_INACTIVE;
+			break;
+		}
+
+		s->count++;
+		if (s->count == BPF_PARAM(bits))
+			s->state = STATE_TRAILER;
+		else
+			s->state = STATE_BITS_PULSE;
+		break;
+	case STATE_TRAILER:
+		if (pulse && eq_margin(BPF_PARAM(trailer_pulse), duration)) {
+			if (s->count == 0)
+				bpf_rc_repeat(sample);
+			else
+				bpf_rc_keydown(sample, BPF_PARAM(rc_protocol), s->bits, 0);
+		}
+
+		s->state = STATE_INACTIVE;
+	}
+
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";