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mouse - mouse and pointing device drivers
The user program simply opens a mouse device with a open(2) call and reads mouse data from the device via read(2). Movement and button states are usually encoded in fixed-length data packets. Some mouse devices may send data in variable length of packets. Actual protocol (data format) used by each driver differs widely.
The mouse drivers may have ``non-blocking'' attribute which will make the driver return immediately if mouse data is not available.
Mouse device drivers often offer several levels of operation. The current operation level can be examined and changed via ioctl(2) commands. The level zero is the lowest level at which the driver offers the basic service to user programs. Most drivers provide horizontal and vertical movement of the mouse and state of up to three buttons at this level. At the level one, if supported by the driver, mouse data is encoded in the standard format MOUSE_PROTO_SYSMOUSE as follows:
The first 5 bytes of this format is compatible with the MouseSystems format. The additional 3 bytes have their MSBs always set to zero. Thus, if the user program can interpret the MouseSystems data format and tries to find the first byte of the format by detecting the bit pattern 10000xxxb, it will discard the additional bytes, thus, be able to decode x, y and states of 3 buttons correctly.
Device drivers may offer operation levels higher than one. Refer to manual pages of individual drivers for details.
typedef struct mousehw {
int buttons; /* number of buttons */
int iftype; /* I/F type */
int type; /* mouse/track ball/pad... */
int model; /* I/F dependent model ID */
int hwid; /* I/F dependent hardware ID */
} mousehw_t;
The buttons field holds the number of buttons detected by the driver. The driver may put an arbitrary value, such as two, in this field, if it cannot determine the exact number.
The iftype is the type of interface: MOUSE_IF_SERIAL MOUSE_IF_BUS MOUSE_IF_INPORT MOUSE_IF_PS2 MOUSE_IF_USB MOUSE_IF_SYSMOUSE or MOUSE_IF_UNKNOWN
The type tells the device type: MOUSE_MOUSE MOUSE_TRACKBALL MOUSE_STICK MOUSE_PAD or MOUSE_UNKNOWN
The model may be MOUSE_MODEL_GENERIC or one of MOUSE_MODEL_XXX constants.
The hwid is the ID value returned by the pointing device. It depend on the interface type; refer to the manual page of specific mouse drivers for possible values.
typedef struct mousemode {
int protocol; /* MOUSE_PROTO_XXX */
int rate; /* report rate (per sec) */
int resolution; /* MOUSE_RES_XXX, -1 if unknown */
int accelfactor; /* acceleration factor */
int level; /* driver operation level */
int packetsize; /* the length of the data packet */
unsigned char syncmask[2]; /* sync. bits */
} mousemode_t;
The protocol field tells the format in which the device status is returned when the mouse data is read by the user program. It is one of MOUSE_PROTO_XXX constants.
The rate field is the status report rate (reports/sec) at which the device will send movement reports to the host computer. -1 if unknown or not applicable.
The resolution field holds a value specifying resolution of the pointing device. It is a positive value or one of MOUSE_RES_XXX constants.
The accelfactor field holds a value to control acceleration feature. It must be zero or greater. If it is zero, acceleration is disabled.
The packetsize field tells the length of the fixed-size data packet or the length of the fixed part of the variable-length packet. The size depends on the interface type, the device type and model, the protocol and the operation level of the driver.
The array syncmask holds a bit mask and pattern to detect the first byte of the data packet. syncmask[0] is the bit mask to be ANDed with a byte. If the result is equal to syncmask[1] the byte is likely to be the first byte of the data packet. Note that this method of detecting the first byte is not 100% reliable, thus, should be taken only as an advisory measure.
If you do not want to change the current setting of a field, put -1 there. You may also put zero in resolution and rate and the default value for the fields will be selected.
typedef struct mousedata {
int len; /* # of data in the buffer */
int buf[16]; /* data buffer */
} mousedata_t;
The calling process must fill the len field with the number of bytes to be read into the buffer. This command may not be supported by all drivers.
typedef struct mousestatus {
int flags; /* state change flags */
int button; /* button status */
int obutton; /* previous button status */
int dx; /* x movement */
int dy; /* y movement */
int dz; /* z movement */
} mousestatus_t;
The button and obutton fields hold the current and the previous state of the mouse buttons. When a button is pressed, the corresponding bit is set. The mouse drivers may support up to 31 buttons with the bit 0 through 31. Few button bits are defined as MOUSE_BUTTON1DOWN through MOUSE_BUTTON8DOWN The first three buttons correspond to left, middle and right buttons.
If the state of the button has changed since the last MOUSE_GETSTATUS call, the corresponding bit in the flags field will be set. If the mouse has moved since the last call, the MOUSE_POSCHANGED bit in the flags field will also be set.
The other fields hold movement counts since the last MOUSE_GETSTATUS call. The internal counters will be reset after every call to this command.
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