--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/haptic/linux/SDL_syshaptic.c	Mon Aug 25 09:55:03 2008 +0000
@@ -0,0 +1,956 @@
+/*
+    SDL - Simple DirectMedia Layer
+    Copyright (C) 2008 Edgar Simo
+
+    This library is free software; you can redistribute it and/or
+    modify it under the terms of the GNU Lesser General Public
+    License as published by the Free Software Foundation; either
+    version 2.1 of the License, or (at your option) any later version.
+
+    This library 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
+    Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public
+    License along with this library; if not, write to the Free Software
+    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+
+    Sam Lantinga
+    slouken@libsdl.org
+*/
+#include "SDL_config.h"
+
+#ifdef SDL_HAPTIC_LINUX
+
+#include "SDL_haptic.h"
+#include "../SDL_syshaptic.h"
+#include "SDL_joystick.h"
+#include "../../joystick/SDL_sysjoystick.h"     /* For the real SDL_Joystick */
+#include "../../joystick/linux/SDL_sysjoystick_c.h"     /* For joystick hwdata */
+
+#include <unistd.h>             /* close */
+#include <linux/input.h>        /* Force feedback linux stuff. */
+#include <fcntl.h>              /* O_RDWR */
+#include <limits.h>             /* INT_MAX */
+#include <errno.h>              /* errno, strerror */
+#include <math.h>               /* atan2 */
+
+/* Just in case. */
+#ifndef M_PI
+#  define M_PI     3.14159265358979323846
+#endif
+
+
+#define MAX_HAPTICS  32         /* It's doubtful someone has more then 32 evdev */
+
+
+/*
+ * List of available haptic devices.
+ */
+static struct
+{
+    char *fname;                /* Dev path name (like /dev/input/event1) */
+    SDL_Haptic *haptic;         /* Assosciated haptic. */
+} SDL_hapticlist[MAX_HAPTICS];
+
+
+/*
+ * Haptic system hardware data.
+ */
+struct haptic_hwdata
+{
+    int fd;                     /* File descriptor of the device. */
+    char *fname;                /* Points to the name in SDL_hapticlist. */
+};
+
+
+/*
+ * Haptic system effect data.
+ */
+struct haptic_hweffect
+{
+    struct ff_effect effect;    /* The linux kernel effect structure. */
+};
+
+
+
+#define test_bit(nr, addr) \
+   (((1UL << ((nr) & 31)) & (((const unsigned int *) addr)[(nr) >> 5])) != 0)
+#define EV_TEST(ev,f) \
+   if (test_bit((ev), features)) ret |= (f);
+/*
+ * Test whether a device has haptic properties.
+ * Returns available properties or 0 if there are none.
+ */
+static int
+EV_IsHaptic(int fd)
+{
+    unsigned int ret;
+    unsigned long features[1 + FF_MAX / sizeof(unsigned long)];
+
+    /* Ask device for what it has. */
+    ret = 0;
+    if (ioctl(fd, EVIOCGBIT(EV_FF, sizeof(features)), features) < 0) {
+        SDL_SetError("Haptic: Unable to get device's features: %s",
+                     strerror(errno));
+        return -1;
+    }
+
+    /* Convert supported features to SDL_HAPTIC platform-neutral features. */
+    EV_TEST(FF_CONSTANT, SDL_HAPTIC_CONSTANT);
+    EV_TEST(FF_SINE, SDL_HAPTIC_SINE);
+    EV_TEST(FF_SQUARE, SDL_HAPTIC_SQUARE);
+    EV_TEST(FF_TRIANGLE, SDL_HAPTIC_TRIANGLE);
+    EV_TEST(FF_SAW_UP, SDL_HAPTIC_SAWTOOTHUP);
+    EV_TEST(FF_SAW_DOWN, SDL_HAPTIC_SAWTOOTHDOWN);
+    EV_TEST(FF_RAMP, SDL_HAPTIC_RAMP);
+    EV_TEST(FF_SPRING, SDL_HAPTIC_SPRING);
+    EV_TEST(FF_FRICTION, SDL_HAPTIC_FRICTION);
+    EV_TEST(FF_DAMPER, SDL_HAPTIC_DAMPER);
+    EV_TEST(FF_INERTIA, SDL_HAPTIC_INERTIA);
+    EV_TEST(FF_CUSTOM, SDL_HAPTIC_CUSTOM);
+    EV_TEST(FF_GAIN, SDL_HAPTIC_GAIN);
+    EV_TEST(FF_AUTOCENTER, SDL_HAPTIC_AUTOCENTER);
+
+    /* Return what it supports. */
+    return ret;
+}
+
+
+/*
+ * Tests whether a device is a mouse or not.
+ */
+static int
+EV_IsMouse(int fd)
+{
+    unsigned long argp[40];
+
+    /* Ask for supported features. */
+    if (ioctl(fd, EVIOCGBIT(EV_KEY, sizeof(argp)), argp) < 0) {
+        return -1;
+    }
+
+    /* Currently we only test for BTN_MOUSE which can give fake positives. */
+    if (test_bit(BTN_MOUSE, argp) != 0) {
+        return 1;
+    }
+
+    return 0;
+}
+
+/*
+ * Initializes the haptic subsystem by finding available devices.
+ */
+int
+SDL_SYS_HapticInit(void)
+{
+    const char joydev_pattern[] = "/dev/input/event%d";
+    dev_t dev_nums[MAX_HAPTICS];
+    char path[PATH_MAX];
+    struct stat sb;
+    int fd;
+    int i, j, k;
+    int duplicate;
+    int numhaptics;
+
+    numhaptics = 0;
+
+    /* 
+     * Limit amount of checks to MAX_HAPTICS since we may or may not have
+     * permission to some or all devices.
+     */
+    i = 0;
+    for (j = 0; j < MAX_HAPTICS; ++j) {
+
+        snprintf(path, PATH_MAX, joydev_pattern, i++);
+
+        /* check to see if file exists */
+        if (stat(path, &sb) != 0)
+            break;
+
+        /* check for duplicates */
+        duplicate = 0;
+        for (k = 0; (k < numhaptics) && !duplicate; ++k) {
+            if (sb.st_rdev == dev_nums[k]) {
+                duplicate = 1;
+            }
+        }
+        if (duplicate) {
+            continue;
+        }
+
+        /* try to open */
+        fd = open(path, O_RDWR, 0);
+        if (fd < 0)
+            continue;
+
+#ifdef DEBUG_INPUT_EVENTS
+        printf("Checking %s\n", path);
+#endif
+
+        /* see if it works */
+        if (EV_IsHaptic(fd) > 0) {
+            SDL_hapticlist[numhaptics].fname = SDL_strdup(path);
+            SDL_hapticlist[numhaptics].haptic = NULL;
+            dev_nums[numhaptics] = sb.st_rdev;
+            ++numhaptics;
+        }
+        close(fd);
+    }
+
+    return numhaptics;
+}
+
+
+/*
+ * Gets the name from a file descriptor.
+ */
+static const char *
+SDL_SYS_HapticNameFromFD(int fd)
+{
+    static char namebuf[128];
+
+    /* We use the evdev name ioctl. */
+    if (ioctl(fd, EVIOCGNAME(sizeof(namebuf)), namebuf) <= 0) {
+        return NULL;
+    }
+
+    return namebuf;
+}
+
+
+/*
+ * Return the name of a haptic device, does not need to be opened.
+ */
+const char *
+SDL_SYS_HapticName(int index)
+{
+    int fd;
+    const char *name;
+
+    /* Open the haptic device. */
+    name = NULL;
+    fd = open(SDL_hapticlist[index].fname, O_RDONLY, 0);
+
+    if (fd >= 0) {
+
+        name = SDL_SYS_HapticNameFromFD(fd);
+        if (name == NULL) {
+            /* No name found, return device character device */
+            name = SDL_hapticlist[index].fname;
+        }
+    }
+    close(fd);
+
+    return name;
+}
+
+
+/*
+ * Opens the haptic device from the file descriptor.
+ */
+static int
+SDL_SYS_HapticOpenFromFD(SDL_Haptic * haptic, int fd)
+{
+    const char *name;
+
+    /* Allocate the hwdata */
+    haptic->hwdata = (struct haptic_hwdata *)
+        SDL_malloc(sizeof(*haptic->hwdata));
+    if (haptic->hwdata == NULL) {
+        SDL_OutOfMemory();
+        goto open_err;
+    }
+    SDL_memset(haptic->hwdata, 0, sizeof(*haptic->hwdata));
+
+    /* Set the data. */
+    haptic->hwdata->fd = fd;
+    haptic->supported = EV_IsHaptic(fd);
+    haptic->naxes = 2;          /* Hardcoded for now, not sure if it's possible to find out. */
+
+    /* Set the effects */
+    if (ioctl(fd, EVIOCGEFFECTS, &haptic->neffects) < 0) {
+        SDL_SetError("Haptic: Unable to query device memory: %s",
+                     strerror(errno));
+        goto open_err;
+    }
+    haptic->nplaying = haptic->neffects;        /* Linux makes no distinction. */
+    haptic->effects = (struct haptic_effect *)
+        SDL_malloc(sizeof(struct haptic_effect) * haptic->neffects);
+    if (haptic->effects == NULL) {
+        SDL_OutOfMemory();
+        goto open_err;
+    }
+    /* Clear the memory */
+    SDL_memset(haptic->effects, 0,
+               sizeof(struct haptic_effect) * haptic->neffects);
+
+    return 0;
+
+    /* Error handling */
+  open_err:
+    close(fd);
+    if (haptic->hwdata != NULL) {
+        free(haptic->hwdata);
+        haptic->hwdata = NULL;
+    }
+    return -1;
+}
+
+
+/*
+ * Opens a haptic device for usage.
+ */
+int
+SDL_SYS_HapticOpen(SDL_Haptic * haptic)
+{
+    int fd;
+    int ret;
+
+    /* Open the character device */
+    fd = open(SDL_hapticlist[haptic->index].fname, O_RDWR, 0);
+    if (fd < 0) {
+        SDL_SetError("Haptic: Unable to open %s: %s",
+                     SDL_hapticlist[haptic->index], strerror(errno));
+        return -1;
+    }
+
+    /* Try to create the haptic. */
+    ret = SDL_SYS_HapticOpenFromFD(haptic, fd); /* Already closes on error. */
+    if (ret < 0) {
+        return -1;
+    }
+
+    /* Set the fname. */
+    haptic->hwdata->fname = SDL_hapticlist[haptic->index].fname;
+    return 0;
+}
+
+
+/*
+ * Opens a haptic device from first mouse it finds for usage.
+ */
+int
+SDL_SYS_HapticMouse(void)
+{
+    int fd;
+    int i;
+
+    for (i = 0; i < SDL_numhaptics; i++) {
+
+        /* Open the device. */
+        fd = open(SDL_hapticlist[i].fname, O_RDWR, 0);
+        if (fd < 0) {
+            SDL_SetError("Haptic: Unable to open %s: %s",
+                         SDL_hapticlist[i], strerror(errno));
+            return -1;
+        }
+
+        /* Is it a mouse? */
+        if (EV_IsMouse(fd)) {
+            close(fd);
+            return i;
+        }
+
+        close(fd);
+    }
+
+    return -1;
+}
+
+
+/*
+ * Checks to see if a joystick has haptic features.
+ */
+int
+SDL_SYS_JoystickIsHaptic(SDL_Joystick * joystick)
+{
+    return EV_IsHaptic(joystick->hwdata->fd);
+}
+
+
+/*
+ * Checks to see if the haptic device and joystick and in reality the same.
+ */
+int
+SDL_SYS_JoystickSameHaptic(SDL_Haptic * haptic, SDL_Joystick * joystick)
+{
+    /* We are assuming linux is using evdev which should trump the old
+     * joystick methods. */
+    if (SDL_strcmp(joystick->hwdata->fname, haptic->hwdata->fname) == 0) {
+        return 1;
+    }
+    return 0;
+}
+
+
+/*
+ * Opens a SDL_Haptic from a SDL_Joystick.
+ */
+int
+SDL_SYS_HapticOpenFromJoystick(SDL_Haptic * haptic, SDL_Joystick * joystick)
+{
+    int i;
+    int fd;
+    int ret;
+
+    /* Find the joystick in the haptic list. */
+    for (i = 0; i < MAX_HAPTICS; i++) {
+        if (SDL_hapticlist[i].fname != NULL) {
+            if (SDL_strcmp(SDL_hapticlist[i].fname, joystick->hwdata->fname)
+                == 0) {
+                haptic->index = i;
+            }
+        }
+    }
+
+    fd = open(joystick->hwdata->fname, O_RDWR, 0);
+    ret = SDL_SYS_HapticOpenFromFD(haptic, fd); /* Already closes on error. */
+    if (ret < 0) {
+        return -1;
+    }
+
+    haptic->hwdata->fname = SDL_hapticlist[haptic->index].fname;
+    return 0;
+}
+
+
+/*
+ * Closes the haptic device.
+ */
+void
+SDL_SYS_HapticClose(SDL_Haptic * haptic)
+{
+    if (haptic->hwdata) {
+
+        /* Free effects. */
+        SDL_free(haptic->effects);
+        haptic->effects = NULL;
+        haptic->neffects = 0;
+
+        /* Clean up */
+        close(haptic->hwdata->fd);
+
+        /* Free */
+        SDL_free(haptic->hwdata);
+        haptic->hwdata = NULL;
+    }
+
+    /* Clear the rest. */
+    SDL_memset(haptic, 0, sizeof(SDL_Haptic));
+}
+
+
+/* 
+ * Clean up after system specific haptic stuff
+ */
+void
+SDL_SYS_HapticQuit(void)
+{
+    int i;
+
+    for (i = 0; SDL_hapticlist[i].fname != NULL; i++) {
+        /* Opened and not closed haptics are leaked, this is on purpose.
+         * Close your haptic devices after usage. */
+
+        SDL_free(SDL_hapticlist[i].fname);
+    }
+    SDL_hapticlist[0].fname = NULL;
+}
+
+
+/*
+ * Converts an SDL button to a ff_trigger button.
+ */
+static Uint16
+SDL_SYS_ToButton(Uint16 button)
+{
+    Uint16 ff_button;
+
+    ff_button = 0;
+
+    /*
+     * Not sure what the proper syntax is because this actually isn't implemented
+     * in the current kernel from what I've seen (2.6.26).
+     */
+    if (button != 0) {
+        ff_button = BTN_GAMEPAD + button - 1;
+    }
+
+    return ff_button;
+}
+
+
+/*
+ * Returns the ff_effect usable direction from a SDL_HapticDirection.
+ */
+static Uint16
+SDL_SYS_ToDirection(SDL_HapticDirection * dir)
+{
+    Uint32 tmp;
+    float f;                    /* Ideally we'd use fixed point math instead of floats... */
+
+    switch (dir->type) {
+    case SDL_HAPTIC_POLAR:
+        /* Linux directions are inverted. */
+        tmp = (((18000 + dir->dir[0]) % 36000) * 0xFFFF) / 36000;
+        return (Uint16) tmp;
+
+    case SDL_HAPTIC_CARTESIAN:
+        /* We must invert "x" and "y" to go clockwise. */
+        f = atan2(dir->dir[0], dir->dir[1]);
+        tmp = (int) (f * 18000. / M_PI) % 36000;
+        tmp = (tmp * 0xFFFF) / 36000;
+        return (Uint16) tmp;
+
+    case SDL_HAPTIC_SPHERICAL:
+        tmp = (36000 - dir->dir[0]) + 27000;    /* Convert to polars */
+        tmp = (((18000 + tmp) % 36000) * 0xFFFF) / 36000;
+        return (Uint16) tmp;
+
+    default:
+        SDL_SetError("Haptic: Unsupported direction type.");
+        return (Uint16) - 1;
+    }
+
+    return 0;
+}
+
+
+#define  CLAMP(x)    (((x) > 32767) ? 32767 : x)
+/*
+ * Initializes the linux effect struct from a haptic_effect.
+ * Values above 32767 (for unsigned) are unspecified so we must clamp.
+ */
+static int
+SDL_SYS_ToFFEffect(struct ff_effect *dest, SDL_HapticEffect * src)
+{
+    Uint32 tmp;
+    SDL_HapticConstant *constant;
+    SDL_HapticPeriodic *periodic;
+    SDL_HapticCondition *condition;
+    SDL_HapticRamp *ramp;
+
+    /* Clear up */
+    SDL_memset(dest, 0, sizeof(struct ff_effect));
+
+    switch (src->type) {
+    case SDL_HAPTIC_CONSTANT:
+        constant = &src->constant;
+
+        /* Header */
+        dest->type = FF_CONSTANT;
+        dest->direction = SDL_SYS_ToDirection(&constant->direction);
+        if (dest->direction == (Uint16) - 1)
+            return -1;
+
+        /* Replay */
+        dest->replay.length = (constant->length == SDL_HAPTIC_INFINITY) ?
+            0 : CLAMP(constant->length);
+        dest->replay.delay = CLAMP(constant->delay);
+
+        /* Trigger */
+        dest->trigger.button = SDL_SYS_ToButton(constant->button);
+        dest->trigger.interval = CLAMP(constant->interval);
+
+        /* Constant */
+        dest->u.constant.level = constant->level;
+
+        /* Envelope */
+        dest->u.constant.envelope.attack_length =
+            CLAMP(constant->attack_length);
+        dest->u.constant.envelope.attack_level =
+            CLAMP(constant->attack_level);
+        dest->u.constant.envelope.fade_length = CLAMP(constant->fade_length);
+        dest->u.constant.envelope.fade_level = CLAMP(constant->fade_level);
+
+        break;
+
+    case SDL_HAPTIC_SINE:
+    case SDL_HAPTIC_SQUARE:
+    case SDL_HAPTIC_TRIANGLE:
+    case SDL_HAPTIC_SAWTOOTHUP:
+    case SDL_HAPTIC_SAWTOOTHDOWN:
+        periodic = &src->periodic;
+
+        /* Header */
+        dest->type = FF_PERIODIC;
+        dest->direction = SDL_SYS_ToDirection(&periodic->direction);
+        if (dest->direction == (Uint16) - 1)
+            return -1;
+
+        /* Replay */
+        dest->replay.length = (periodic->length == SDL_HAPTIC_INFINITY) ?
+            0 : CLAMP(periodic->length);
+        dest->replay.delay = CLAMP(periodic->delay);
+
+        /* Trigger */
+        dest->trigger.button = SDL_SYS_ToButton(periodic->button);
+        dest->trigger.interval = CLAMP(periodic->interval);
+
+        /* Periodic */
+        if (periodic->type == SDL_HAPTIC_SINE)
+            dest->u.periodic.waveform = FF_SINE;
+        else if (periodic->type == SDL_HAPTIC_SQUARE)
+            dest->u.periodic.waveform = FF_SQUARE;
+        else if (periodic->type == SDL_HAPTIC_TRIANGLE)
+            dest->u.periodic.waveform = FF_TRIANGLE;
+        else if (periodic->type == SDL_HAPTIC_SAWTOOTHUP)
+            dest->u.periodic.waveform = FF_SAW_UP;
+        else if (periodic->type == SDL_HAPTIC_SAWTOOTHDOWN)
+            dest->u.periodic.waveform = FF_SAW_DOWN;
+        dest->u.periodic.period = CLAMP(periodic->period);
+        dest->u.periodic.magnitude = periodic->magnitude;
+        dest->u.periodic.offset = periodic->offset;
+        /* Phase is calculated based of offset from period and then clamped. */
+        tmp = ((periodic->phase % 36000) * dest->u.periodic.period) / 36000;
+        dest->u.periodic.phase = CLAMP(tmp);
+
+        /* Envelope */
+        dest->u.periodic.envelope.attack_length =
+            CLAMP(periodic->attack_length);
+        dest->u.periodic.envelope.attack_level =
+            CLAMP(periodic->attack_level);
+        dest->u.periodic.envelope.fade_length = CLAMP(periodic->fade_length);
+        dest->u.periodic.envelope.fade_level = CLAMP(periodic->fade_level);
+
+        break;
+
+    case SDL_HAPTIC_SPRING:
+    case SDL_HAPTIC_DAMPER:
+    case SDL_HAPTIC_INERTIA:
+    case SDL_HAPTIC_FRICTION:
+        condition = &src->condition;
+
+        /* Header */
+        if (condition->type == SDL_HAPTIC_SPRING)
+            dest->type = FF_SPRING;
+        else if (condition->type == SDL_HAPTIC_DAMPER)
+            dest->type = FF_DAMPER;
+        else if (condition->type == SDL_HAPTIC_INERTIA)
+            dest->type = FF_INERTIA;
+        else if (condition->type == SDL_HAPTIC_FRICTION)
+            dest->type = FF_FRICTION;
+        dest->direction = 0;    /* Handled by the condition-specifics. */
+
+        /* Replay */
+        dest->replay.length = (condition->length == SDL_HAPTIC_INFINITY) ?
+            0 : CLAMP(condition->length);
+        dest->replay.delay = CLAMP(condition->delay);
+
+        /* Trigger */
+        dest->trigger.button = SDL_SYS_ToButton(condition->button);
+        dest->trigger.interval = CLAMP(condition->interval);
+
+        /* Condition */
+        /* X axis */
+        dest->u.condition[0].right_saturation =
+            CLAMP(condition->right_sat[0]);
+        dest->u.condition[0].left_saturation = CLAMP(condition->left_sat[0]);
+        dest->u.condition[0].right_coeff = condition->right_coeff[0];
+        dest->u.condition[0].left_coeff = condition->left_coeff[0];
+        dest->u.condition[0].deadband = CLAMP(condition->deadband[0]);
+        dest->u.condition[0].center = condition->center[0];
+        /* Y axis */
+        dest->u.condition[1].right_saturation =
+            CLAMP(condition->right_sat[1]);
+        dest->u.condition[1].left_saturation = CLAMP(condition->left_sat[1]);
+        dest->u.condition[1].right_coeff = condition->right_coeff[1];
+        dest->u.condition[1].left_coeff = condition->left_coeff[1];
+        dest->u.condition[1].deadband = CLAMP(condition->deadband[1]);
+        dest->u.condition[1].center = condition->center[1];
+
+        /*
+         * There is no envelope in the linux force feedback api for conditions.
+         */
+
+        break;
+
+    case SDL_HAPTIC_RAMP:
+        ramp = &src->ramp;
+
+        /* Header */
+        dest->type = FF_RAMP;
+        dest->direction = SDL_SYS_ToDirection(&ramp->direction);
+        if (dest->direction == (Uint16) - 1)
+            return -1;
+
+        /* Replay */
+        dest->replay.length = (ramp->length == SDL_HAPTIC_INFINITY) ?
+            0 : CLAMP(ramp->length);
+        dest->replay.delay = CLAMP(ramp->delay);
+
+        /* Trigger */
+        dest->trigger.button = SDL_SYS_ToButton(ramp->button);
+        dest->trigger.interval = CLAMP(ramp->interval);
+
+        /* Ramp */
+        dest->u.ramp.start_level = ramp->start;
+        dest->u.ramp.end_level = ramp->end;
+
+        /* Envelope */
+        dest->u.ramp.envelope.attack_length = CLAMP(ramp->attack_length);
+        dest->u.ramp.envelope.attack_level = CLAMP(ramp->attack_level);
+        dest->u.ramp.envelope.fade_length = CLAMP(ramp->fade_length);
+        dest->u.ramp.envelope.fade_level = CLAMP(ramp->fade_level);
+
+        break;
+
+
+    default:
+        SDL_SetError("Haptic: Unknown effect type.");
+        return -1;
+    }
+
+    return 0;
+}
+
+
+/*
+ * Creates a new haptic effect.
+ */
+int
+SDL_SYS_HapticNewEffect(SDL_Haptic * haptic, struct haptic_effect *effect,
+                        SDL_HapticEffect * base)
+{
+    struct ff_effect *linux_effect;
+
+    /* Allocate the hardware effect */
+    effect->hweffect = (struct haptic_hweffect *)
+        SDL_malloc(sizeof(struct haptic_hweffect));
+    if (effect->hweffect == NULL) {
+        SDL_OutOfMemory();
+        return -1;
+    }
+
+    /* Prepare the ff_effect */
+    linux_effect = &effect->hweffect->effect;
+    if (SDL_SYS_ToFFEffect(linux_effect, base) != 0) {
+        goto new_effect_err;
+    }
+    linux_effect->id = -1;      /* Have the kernel give it an id */
+
+    /* Upload the effect */
+    if (ioctl(haptic->hwdata->fd, EVIOCSFF, linux_effect) < 0) {
+        SDL_SetError("Haptic: Error uploading effect to the device: %s",
+                     strerror(errno));
+        goto new_effect_err;
+    }
+
+    return 0;
+
+  new_effect_err:
+    free(effect->hweffect);
+    effect->hweffect = NULL;
+    return -1;
+}
+
+
+/*
+ * Updates an effect.
+ *
+ * Note: Dynamically updating the direction can in some cases force
+ * the effect to restart and run once.
+ */
+int
+SDL_SYS_HapticUpdateEffect(SDL_Haptic * haptic,
+                           struct haptic_effect *effect,
+                           SDL_HapticEffect * data)
+{
+    struct ff_effect linux_effect;
+
+    /* Create the new effect */
+    if (SDL_SYS_ToFFEffect(&linux_effect, data) != 0) {
+        return -1;
+    }
+    linux_effect.id = effect->hweffect->effect.id;
+
+    /* See if it can be uploaded. */
+    if (ioctl(haptic->hwdata->fd, EVIOCSFF, &linux_effect) < 0) {
+        SDL_SetError("Haptic: Error updating the effect: %s",
+                     strerror(errno));
+        return -1;
+    }
+
+    /* Copy the new effect into memory. */
+    SDL_memcpy(&effect->hweffect->effect, &linux_effect,
+               sizeof(struct ff_effect));
+
+    return effect->hweffect->effect.id;
+}
+
+
+/*
+ * Runs an effect.
+ */
+int
+SDL_SYS_HapticRunEffect(SDL_Haptic * haptic, struct haptic_effect *effect,
+                        Uint32 iterations)
+{
+    struct input_event run;
+
+    /* Prepare to run the effect */
+    run.type = EV_FF;
+    run.code = effect->hweffect->effect.id;
+    /* We don't actually have infinity here, so we just do INT_MAX which is pretty damn close. */
+    run.value = (iterations > INT_MAX) ? INT_MAX : iterations;
+
+    if (write(haptic->hwdata->fd, (const void *) &run, sizeof(run)) < 0) {
+        SDL_SetError("Haptic: Unable to run the effect: %s", strerror(errno));
+        return -1;
+    }
+
+    return 0;
+}
+
+
+/*
+ * Stops an effect.
+ */
+int
+SDL_SYS_HapticStopEffect(SDL_Haptic * haptic, struct haptic_effect *effect)
+{
+    struct input_event stop;
+
+    stop.type = EV_FF;
+    stop.code = effect->hweffect->effect.id;
+    stop.value = 0;
+
+    if (write(haptic->hwdata->fd, (const void *) &stop, sizeof(stop)) < 0) {
+        SDL_SetError("Haptic: Unable to stop the effect: %s",
+                     strerror(errno));
+        return -1;
+    }
+
+    return 0;
+}
+
+
+/*
+ * Frees the effect.
+ */
+void
+SDL_SYS_HapticDestroyEffect(SDL_Haptic * haptic, struct haptic_effect *effect)
+{
+    if (ioctl(haptic->hwdata->fd, EVIOCRMFF, effect->hweffect->effect.id) < 0) {
+        SDL_SetError("Haptic: Error removing the effect from the device: %s",
+                     strerror(errno));
+    }
+    SDL_free(effect->hweffect);
+    effect->hweffect = NULL;
+}
+
+
+/*
+ * Gets the status of a haptic effect.
+ */
+int
+SDL_SYS_HapticGetEffectStatus(SDL_Haptic * haptic,
+                              struct haptic_effect *effect)
+{
+#if 0                           /* Not supported atm. */
+    struct input_event ie;
+
+    ie.type = EV_FF;
+    ie.type = EV_FF_STATUS;
+    ie.code = effect->hweffect->effect.id;
+
+    if (write(haptic->hwdata->fd, &ie, sizeof(ie)) < 0) {
+        SDL_SetError("Haptic: Error getting device status.");
+        return -1;
+    }
+
+    return 0;
+#endif
+
+    return -1;
+}
+
+
+/*
+ * Sets the gain.
+ */
+int
+SDL_SYS_HapticSetGain(SDL_Haptic * haptic, int gain)
+{
+    struct input_event ie;
+
+    ie.type = EV_FF;
+    ie.code = FF_GAIN;
+    ie.value = (0xFFFFUL * gain) / 100;
+
+    if (write(haptic->hwdata->fd, &ie, sizeof(ie)) < 0) {
+        SDL_SetError("Haptic: Error setting gain: %s", strerror(errno));
+        return -1;
+    }
+
+    return 0;
+}
+
+
+/*
+ * Sets the autocentering.
+ */
+int
+SDL_SYS_HapticSetAutocenter(SDL_Haptic * haptic, int autocenter)
+{
+    struct input_event ie;
+
+    ie.type = EV_FF;
+    ie.code = FF_AUTOCENTER;
+    ie.value = (0xFFFFUL * autocenter) / 100;
+
+    if (write(haptic->hwdata->fd, &ie, sizeof(ie)) < 0) {
+        SDL_SetError("Haptic: Error setting autocenter: %s", strerror(errno));
+        return -1;
+    }
+
+    return 0;
+}
+
+
+/*
+ * Pausing is not supported atm by linux.
+ */
+int
+SDL_SYS_HapticPause(SDL_Haptic * haptic)
+{
+    return -1;
+}
+
+
+/*
+ * Unpausing is not supported atm by linux.
+ */
+int
+SDL_SYS_HapticUnpause(SDL_Haptic * haptic)
+{
+    return -1;
+}
+
+
+/*
+ * Stops all the currently playing effects.
+ */
+int
+SDL_SYS_HapticStopAll(SDL_Haptic * haptic)
+{
+    int i, ret;
+
+    /* Linux does not support this natively so we have to loop. */
+    for (i = 0; i < haptic->neffects; i++) {
+        if (haptic->effects[i].hweffect != NULL) {
+            ret = SDL_SYS_HapticStopEffect(haptic, &haptic->effects[i]);
+            if (ret < 0) {
+                SDL_SetError
+                    ("Haptic: Error while trying to stop all playing effects.");
+                return -1;
+            }
+        }
+    }
+    return 0;
+}
+
+
+#endif /* SDL_HAPTIC_LINUX */