# GX_IsVBlank

## Syntax

      #include <nitro/gx/gx.h>

      s32 GX_IsVBlank();

## Arguments

None.

## Return Values

Not in V-Blank period (0), or in V-Blank period (other than 0).

## Description

This function determines whether the program is in the V-Blank period. It returns a value other than 0 when in the V-Blank period; it returns 0 when not in the V-Blank period.

## Note

The hardware V-Blank flag is set to 1 when line 192 starts and to 0 when line 262 starts. Because the function uses this flag value to determine when the hardware is in a V-Blank period, be aware that the V-Blank period is when the V-counter value is the 192-261 range. This does not include 262.

## See Also

`GX_VBlankIntr`, `GX_IsHBlank`

## Revision History

2005/02/17 Added caution about V-Blank period.
2004/01/19 Initial version.

CONFIDENTIAL