paulo@0: #include <nds.h>
paulo@0: 
paulo@0: /* 
paulo@0: by Mighty Max and melw,
paulo@0: after http://forum.gbadev.org/viewtopic.php?t=12011
paulo@0: */
paulo@0: 
paulo@0: int needLidSleep(void) {
paulo@0:   // when reading keys
paulo@0:   if (IPC->buttons & 0x0080) {
paulo@0:     /* hinge is closed */
paulo@0:     
paulo@0:     /* Step 1: Turn off all interrupts but vblank for waking up */
paulo@0:     unsigned long oldIE = REG_IE;
paulo@0:     REG_IE = IRQ_VBLANK;
paulo@0: 
paulo@0:     /* Step 2: Power off most of the system */
paulo@0:     powerOFF(POWER_LCD);
paulo@0: 
paulo@0:     /* Step 3: Wait one vblank at a time until the ARM7 tells us
paulo@0:        that the lid is no longer closed */
paulo@0:     while (IPC->buttons & 0x0080) {
paulo@0:       swiWaitForVBlank();
paulo@0:     }
paulo@0: 
paulo@0:     /* Step 4: Wait a bit more (necessary?) */
paulo@0:     swiWaitForVBlank();
paulo@0: 
paulo@0:     /* Step 5: Restore old machine state */
paulo@0:     powerON(POWER_LCD);
paulo@0:     REG_IE = oldIE;
paulo@0:     return 1;
paulo@0:   }
paulo@0:   return 0;
paulo@0: }