#include <revolution/kpad.h> s32 KPADRead( s32 chan, KPADStatus samplingBufs[], u32 length );
| chan | One of the WPAD_CHANn values. |
|---|---|
| samplingBufs | Pointer to the KPADStatus structure. |
| length | Maximum number of data sets to store. If you use the KPADInit function, this number cannot exceed KPAD_RING_BUFS. If you use the KPADInitEx function, this value cannot exceed the sum of KPAD_RING_BUFS and one-quarter the array length passed to the KPADInitEx function. |
Returns the number of data sets that are stored.
Note, however, that the buffer specified by samplingBufs may be used internally as a work area. Contents of the buffer may therefore be rewritten even if the return value is zero, and values stored in the buffer cannot be guaranteed. When the return value is zero, we recommend using the value obtained previously.
Because the Wii console and Wii Remote use wireless communication, cases exist where signal interference in the surroundings would block any data being transmitted between prior and current calls, and the function would return zero. Even in these circumstances the Wii console and Wii Remote maintain their connection status, so their connection status cannot be judged from the return value of this function. To determine connection status, use the WPADProbe or WPADSetConnectCallback function. It is also possible to use the return value of the KPADReadEx function. KPAD_READ_ERR_NO_DATA is used as the return value when data cannot be received. KPAD_READ_ERR_NO_CONTROLLER is used as the return value when not connected.
This function reads data in the KPADStatus structure type for each controller channel. We have assumed that this function will be called for each game frame. The buffer specified by the argument stores, from newest to oldest, the data sampled from the previous call's time to the current call's time. (In other words, the newest data is always stored at the beginning of the buffer.) However, in the case of button information only, if the button processing method obtained using the KPADGetButtonProcMode function is KPAD_BUTTON_PROC_MODE_LOOSE, only the most recent values are accessed when the KPADRead or KPADReadEx functions are called, and those values are copied into all the current-frame sampling buffers.
The buffer specified by samplingBufs is sometimes used internally as a work area. Because of this, it is possible for buffer contents to be overwritten even when there was no data.
Note: Under certain circumstances, the KPADRead function returns 0 for a fixed period of time. (This indicates that it failed to obtain the data.) For more information about when this can occur and a workaround, see Notes Regarding Read/Writes to Wii Console NAND Memory.
2010/05/28 Added note about the continual return of 0 for a set period of time.
2009/01/07 Added a description of KPADReadEx.
2008/06/13 Revised the explanation of length. Added explanation of the differences caused by different button processing methods.
2008/06/03 Deleted error codes.
2008/04/17 Revised the description of length. Added error codes.
2007/08/27 Explained that this function's return value cannot be used to judge connection status, and to use prior obtained values when the return value is zero.
2006/10/25 Revised the description to match KPAD version 2.
2006/08/xx Added a link under See Also.
2006/03/01 Initial version.
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