refactor: Introduce mtdev

With the addition of the kernel MT slots, the MT event protocol
is capable of efficiently propagating changes to a set of tracked
contacts. At the same time, the need to treat a variety of different
kernel drivers is increased. This patch introduces the mtdev, an
abstract MT device which converts all valid MT event formats into
a uniform, slotted type B event stream. A command-line test program
is included.

Signed-off-by: Henrik Rydberg <rydberg@euromail.se>

2 files changed, 481 insertions, 0 deletions

diff --git a/mtdev/core.c b/mtdev/core.c
new file mode 100644
index 0000000..c8eae37
--- /dev/null
+++ b/mtdev/core.c
@@ -0,0 +1,402 @@
+/***************************************************************************
+ *
+ * Multitouch X driver
+ * Copyright (C) 2008 Henrik Rydberg <rydberg@euromail.se>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ **************************************************************************/
+
+#include "mtdev.h"
+#include "mtbit.h"
+
+/**
+ * struct MTSlot - represents the state of an input MT slot
+ * @abs: current values of ABS_MT axes for this slot
+ */
+struct MTSlot {
+        int abs[MT_ABS_SIZE];
+};
+
+/**
+ * struct MTDevState - MT slot parsing
+ * @data: array of scratch slot data
+ * @used: bitmask of currently used slots
+ * @slot: slot currently being modified
+ * @lastid: last used tracking id
+ */
+struct MTDevState {
+        struct MTSlot data[DIM_FINGER];
+        bitmask_t used;
+        bitmask_t slot;
+        bitmask_t lastid;
+};
+
+/**
+ * mtdev_init - init MT device
+ * @dev: device to initialize
+ * @caps: device capabilities
+ */
+int mtdev_init(struct MTDev *dev, const struct Capabilities *caps)
+{
+        memset(dev, 0, sizeof(struct MTDev));
+        if (!caps->has_mtdata)
+                return -ENODEV;
+        if (!caps->has_slot) {
+                dev->priv = calloc(1, sizeof(struct MTDevState));
+                if (!dev->priv)
+                        return -ENOMEM;
+        }
+        return 0;
+}
+
+static inline int istouch(const struct MTSlot *data,
+                          const struct Capabilities *caps)
+{
+        return data->abs[BIT_TOUCH_MAJOR] || !caps->has_abs[BIT_TOUCH_MAJOR];
+}
+
+/* Dmitry Torokhov's code from kernel/driver/input/input.c */
+static int defuzz(int value, int old_val, int fuzz)
+{
+        if (fuzz) {
+                if (value > old_val - fuzz / 2 && value < old_val + fuzz / 2)
+                        return old_val;
+
+                if (value > old_val - fuzz && value < old_val + fuzz)
+                        return (old_val * 3 + value) / 4;
+
+                if (value > old_val - fuzz * 2 && value < old_val + fuzz * 2)
+                        return (old_val + value) / 2;
+        }
+
+        return value;
+}
+
+/*
+ * solve - solve contact matching problem
+ * @priv: parsing state
+ * @caps: device capabilities
+ * @sid: array of current tracking ids
+ * @sx: array of current position x
+ * @sy: array of current position y
+ * @sn: number of current contacts
+ * @nid: array of new or matched tracking ids, to be filled
+ * @nx: array of new position x
+ * @ny: array of new position y
+ * @nn: number of new contacts
+ * @touch: which of the new contacts to fill
+ */
+static void solve(struct MTDevState *priv, const struct Capabilities *caps,
+                  const int *sid, const int *sx, const int *sy, int sn,
+                  int *nid, const int *nx, const int *ny, int nn,
+                  bitmask_t touch)
+{
+        int A[DIM2_FINGER], *row;
+        int n2s[DIM_FINGER];
+        int id, i, j;
+
+        /* setup distance matrix for contact matching */
+        for (j = 0; j < sn; j++) {
+                row = A + nn * j;
+                for (i = 0; i < nn; i++)
+                        row[i] = dist2(nx[i] - sx[j], ny[i] - sy[j]);
+        }
+
+        match_fingers(n2s, A, nn, sn);
+
+        /* update matched contacts and create new ones */
+        foreach_bit(i, touch) {
+                j = n2s[i];
+                id = j >= 0 ? sid[j] : caps->nullid;
+                while (id == caps->nullid)
+                        id = ++priv->lastid;
+                nid[i] = id;
+        }
+}
+
+/*
+ * assign_tracking_id - assign tracking ids to all contacts
+ * @priv: parsing state
+ * @caps: device capabilities
+ * @data: array of all present contacts, to be filled
+ * @prop: array of all set contacts properties
+ * @size: number of contacts in array
+ * @touch: which of the contacts are actual touches
+ */
+static void assign_tracking_id(struct MTDevState *priv,
+                               const struct Capabilities *caps,
+                               struct MTSlot *data, bitmask_t *prop,
+                               int size, bitmask_t touch)
+{
+        int sid[DIM_FINGER], sx[DIM_FINGER], sy[DIM_FINGER], sn = 0;
+        int nid[DIM_FINGER], nx[DIM_FINGER], ny[DIM_FINGER], i;
+        foreach_bit(i, priv->used) {
+                sid[sn] = priv->data[i].abs[BIT_TRACKING_ID];
+                sx[sn] = priv->data[i].abs[BIT_POSITION_X];
+                sy[sn] = priv->data[i].abs[BIT_POSITION_Y];
+                sn++;
+        }
+        for (i = 0; i < size; i++) {
+                nx[i] = data[i].abs[BIT_POSITION_X];
+                ny[i] = data[i].abs[BIT_POSITION_Y];
+        }
+        solve(priv, caps, sid, sx, sy, sn, nid, nx, ny, size, touch);
+        for (i = 0; i < size; i++) {
+                data[i].abs[BIT_TRACKING_ID] =
+                        GETBIT(touch, i) ? nid[i] : caps->nullid;
+                prop[i] |= BITMASK(BIT_TRACKING_ID);
+        }
+}
+
+/*
+ * process_typeA - consume MT events and update parsing state
+ * @dev: MT device
+ * @data: array of all present contacts, to be filled
+ * @prop: array of all set contacts properties, to be filled
+ *
+ * This function is called when a SYN_REPORT is seen, right before
+ * that event is pushed to the queue.
+ *
+ * Returns -1 if the packet is not MT related and should not affect
+ * the current parsing state.
+ */
+static int process_typeA(struct MTDev *dev,
+                         struct MTSlot *data, bitmask_t *prop)
+{
+        struct input_event ev;
+        int consumed, mtcode;
+        int mtcnt = 0, size = 0;
+        prop[size] = 0;
+        while (!evbuf_empty(&dev->inbuf)) {
+                evbuf_pop(&dev->inbuf, &ev);
+                consumed = 0;
+                switch (ev.type) {
+                case EV_SYN:
+                        switch (ev.code) {
+                        case SYN_MT_REPORT:
+                                if (size < DIM_FINGER &&
+                                    GETBIT(prop[size], BIT_POSITION_X) &&
+                                    GETBIT(prop[size], BIT_POSITION_Y))
+                                        size++;
+                                if (size < DIM_FINGER)
+                                        prop[size] = 0;
+                                mtcnt++;
+                                consumed = 1;
+                                break;
+                        }
+                        break;
+                case EV_KEY:
+                        switch (ev.code) {
+                        case BTN_TOUCH:
+                                mtcnt++;
+                                break;
+                        }
+                        break;
+                case EV_ABS:
+                        if (size < DIM_FINGER && has_abs2mt(ev.code)) {
+                                mtcode = abs2mt(ev.code);
+                                data[size].abs[mtcode] = ev.value;
+                                prop[size] |= BITMASK(mtcode);
+                                mtcnt++;
+                                consumed = 1;
+                        }
+                        break;
+                }
+                if (!consumed)
+                        evbuf_push(&dev->outbuf, &ev);
+        }
+        return mtcnt ? size : -1;
+}
+
+/*
+ * process_typeB - propagate events without parsing
+ * @dev: MT device
+ *
+ * This function is called when a SYN_REPORT is seen, right before
+ * that event is pushed to the queue.
+ */
+static void process_typeB(struct MTDev *dev)
+{
+        struct input_event ev;
+        while (!evbuf_empty(&dev->inbuf)) {
+                evbuf_pop(&dev->inbuf, &ev);
+                evbuf_push(&dev->outbuf, &ev);
+        }
+}
+
+/*
+ * filter_data - apply input filtering on new incoming data
+ * @priv: parsing state
+ * @caps: device capabilities
+ * @data: the incoming data to filter
+ * @prop: the properties to filter
+ * @slot: the slot the data refers to
+ */
+static void filter_data(const struct MTDevState *priv,
+                        const struct Capabilities *caps,
+                        struct MTSlot *data, bitmask_t prop,
+                        int slot)
+{
+        int i;
+        foreach_bit(i, prop) {
+                int fuzz = caps->abs[i].fuzz;
+                int oldval = priv->data[slot].abs[i];
+                data->abs[i] = defuzz(data->abs[i], oldval, fuzz);
+        }
+}
+
+/*
+ * push_slot_changes - propagate state changes
+ * @dev: MT device
+ * @data: the incoming data to propagate
+ * @prop: the properties to propagate
+ * @slot: the slot the data refers to
+ * @syn: reference to the SYN_REPORT event
+ */
+static void push_slot_changes(struct MTDev *dev,
+                              const struct MTSlot *data, bitmask_t prop,
+                              int slot, const struct input_event *syn)
+{
+        struct MTDevState *priv = dev->priv;
+        struct input_event ev;
+        int i, count = 0;
+        foreach_bit(i, prop)
+                if (priv->data[slot].abs[i] != data->abs[i])
+                        count++;
+        if (!count)
+                return;
+        ev.time = syn->time;
+        ev.type = EV_ABS;
+        ev.code = ABS_MT_SLOT;
+        ev.value = slot;
+        if (priv->slot != ev.value) {
+                evbuf_push(&dev->outbuf, &ev);
+                priv->slot = ev.value;
+        }
+        foreach_bit(i, prop) {
+                ev.code = mt2abs(i);
+                ev.value = data->abs[i];
+                if (priv->data[slot].abs[i] != ev.value) {
+                        evbuf_push(&dev->outbuf, &ev);
+                        priv->data[slot].abs[i] = ev.value;
+                }
+        }
+}
+
+/*
+ * apply_typeA_changes - parse and propagate state changes
+ * @dev: MT device
+ * @caps: device capabilities
+ * @data: array of data to apply
+ * @prop: array of properties to apply
+ * @size: number of contacts in array
+ * @syn: reference to the SYN_REPORT event
+ */
+static void apply_typeA_changes(struct MTDev *dev,
+                                const struct Capabilities *caps,
+                                struct MTSlot *data, const bitmask_t *prop,
+                                int size, const struct input_event *syn)
+{
+        struct MTDevState *priv = dev->priv;
+        bitmask_t unused = ~priv->used;
+        bitmask_t used = 0;
+        int i, slot, id;
+        for (i = 0; i < size; i++) {
+                id = data[i].abs[BIT_TRACKING_ID];
+                foreach_bit(slot, priv->used) {
+                        if (priv->data[slot].abs[BIT_TRACKING_ID] != id)
+                                continue;
+                        filter_data(priv, caps, &data[i], prop[i], slot);
+                        push_slot_changes(dev, &data[i], prop[i], slot, syn);
+                        SETBIT(used, slot);
+                        id = caps->nullid;
+                        break;
+                }
+                if (id != caps->nullid) {
+                        slot = firstbit(unused);
+                        push_slot_changes(dev, &data[i], prop[i], slot, syn);
+                        SETBIT(used, slot);
+                        CLEARBIT(unused, slot);
+                }
+        }
+
+        /* clear unused slots and update slot usage */
+        foreach_bit(slot, priv->used & ~used) {
+                struct MTSlot tdata = priv->data[slot];
+                bitmask_t tprop = BITMASK(BIT_TRACKING_ID);
+                tdata.abs[BIT_TRACKING_ID] = caps->nullid;
+                push_slot_changes(dev, &tdata, tprop, slot, syn);
+        }
+        priv->used = used;
+}
+
+/*
+ * convert_A_to_B - propagate a type A packet as a type B packet
+ * @dev: MT device
+ * @caps: device capabilities
+ * @syn: reference to the SYN_REPORT event
+ */
+static void convert_A_to_B(struct MTDev *dev,
+                           const struct Capabilities *caps,
+                           const struct input_event *syn)
+{
+        struct MTSlot data[DIM_FINGER];
+        bitmask_t prop[DIM_FINGER];
+        int size = process_typeA(dev, data, prop);
+        if (size < 0)
+                return;
+        if (!caps->has_abs[BIT_TRACKING_ID]) {
+                bitmask_t touch = 0;
+                int i;
+                for (i = 0; i < size; i++)
+                        MODBIT(touch, i, istouch(&data[i], caps));
+                assign_tracking_id(dev->priv, caps, data, prop, size, touch);
+        }
+        apply_typeA_changes(dev, caps, data, prop, size, syn);
+}
+
+/**
+ * mtdev_push - insert event into MT device
+ * @dev: MT device
+ * @caps: device capabilities
+ * @syn: reference to the SYN_REPORT event
+ */
+void mtdev_push(struct MTDev *dev,
+                const struct Capabilities *caps,
+                const struct input_event *ev)
+{
+        if (ev->type == EV_SYN && ev->code == SYN_REPORT) {
+                bitmask_t head = dev->outbuf.head;
+                if (dev->priv)
+                        convert_A_to_B(dev, caps, ev);
+                else
+                        process_typeB(dev);
+                if (dev->outbuf.head != head)
+                        evbuf_push(&dev->outbuf, ev);
+        } else {
+                evbuf_push(&dev->inbuf, ev);
+        }
+}
+
+/**
+ * mtdev_destroy - destroy MT device
+ * @dev: MT device
+ */
+void mtdev_destroy(struct MTDev *dev)
+{
+        free(dev->priv);
+        memset(dev, 0, sizeof(struct MTDev));
+}
diff --git a/mtdev/test.c b/mtdev/test.c
new file mode 100644
index 0000000..bbe4829
--- /dev/null
+++ b/mtdev/test.c
@@ -0,0 +1,79 @@
+/***************************************************************************
+ *
+ * Multitouch X driver
+ * Copyright (C) 2008 Henrik Rydberg <rydberg@euromail.se>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ **************************************************************************/
+
+#include "mtdev-iobuf.h"
+#include "mtdev.h"
+#include <fcntl.h>
+#include <xbypass.h>
+
+static void print_event(const struct input_event *ev)
+{
+        static const mstime_t ms = 1000;
+        static int slot;
+        mstime_t evtime = ev->time.tv_usec / ms + ev->time.tv_sec * ms;
+        if (ev->type == EV_ABS && ev->code == ABS_MT_SLOT)
+                slot = ev->value;
+        fprintf(stderr, "%012llx: %04d: %04x %04x %d\n",
+                evtime, slot, ev->type, ev->code, ev->value);
+}
+
+static void loop_device(int fd)
+{
+        struct Capabilities caps;
+        struct IOBuffer iobuf;
+        struct MTDev mtdev;
+        const struct input_event *ev;
+        struct input_event event;
+        if (read_capabilities(&caps, fd)) {
+                fprintf(stderr, "error: could not read device capabilities\n");
+                return;
+        }
+        output_capabilities(&caps);
+        if (mtdev_init(&mtdev, &caps)) {
+                fprintf(stderr, "error: could not initialize device\n");
+                return;
+        }
+        init_iobuf(&iobuf);
+        while (ev = get_iobuf_event(&iobuf, fd)) {
+                mtdev_push(&mtdev, &caps, ev);
+                while (!mtdev_empty(&mtdev)) {
+                        mtdev_pop(&mtdev, &event);
+                        print_event(&event);
+                }
+        }
+        mtdev_destroy(&mtdev);
+}
+
+int main(int argc, char *argv[])
+{
+        if (argc < 2) {
+                fprintf(stderr, "Usage: test <mtdev>\n");
+                return -1;
+        }
+        int fd = open(argv[1], O_RDONLY);
+        if (fd < 0) {
+                fprintf(stderr, "error: could not open file\n");
+                return -1;
+        }
+        loop_device(fd);
+        close(fd);
+        return 0;
+}