What does getBatteryLevel do?

[Xenon]

I have checked libnds-src to figure out that getBatteryLevel is a FIFO function.
Then I see ARM7 code:

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        battery = readPowerManagement(PM_BATTERY_REG) & 1;
        backlight = readPowerManagement(PM_BACKLIGHT_LEVEL);
        if (backlight & (1<<6)) battery += backlight & (1<<3)<<12;
        fifoSendValue32(FIFO_SYSTEM, battery);

I know almost all of this meaning(1<<6 was formally PM_NDSLITE_ISLITE), but I cannot understand

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battery += backlight & (1<<3)<<12

this is interprted as battery+=(backlight&((1<<3)<<12)), but I don't know what is the meaning of 15th bit of readPowerManagement(PM_BACKLIGHT_LEVEL). Could you tell me?

Or did you mean this?

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battery += (backlight & (1<<3))<<12

1<<3 was formally PM_NDSLITE_ExternalPowerPresent, thus it can be explained.

[StevenH]

There is no 15th bit of the power management registers as they are all 8 bits...

I'm actually looking at that code now, and there's a couple of things that's a little stange to me as well...

I think what it's supposed to be doing is the following:

battery = OK / low power (0 = OK, 1 - Low power according to the GBATEK docs.)
backlight & ( 1 << 6 ) == DSLite check
backlight & ( 1 << 3 ) == Wall power ( 0 = no, 1 = Yes )

therefore from my understanding of the above:

battery = 0 - Green light
battery = 1 - low power
battery = 32768 - green light + wall power
battery = 32769 - low power, but recharging.

This is possibly due to the new features that the DSi has for power levels (5 different levels), and it's something that was needed to be added to the system, the only downside is that the DSi's power management stuff is still needing to be RE'd.

Please note the above is from my limited understanding of the code in the SVN.

Hope the above helps

[Xenon]

If

backlight & ( 1 << 3 ) == Wall power ( 0 = no, 1 = Yes )
battery = 32768 - green light + wall power
battery = 32769 - low power, but recharging.

is meant, I think

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battery += backlight & (1<<3)<<12

should be changed to

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battery += (backlight & (1<<3))<<12

[WinterMute]

meh, that's what I get for not testing "simple" code when I assume operator priority.

Fixed in libnds 1.4.7

[Xenon]

Thank you for fixing.

[lazyprogramer]

sorry, I dind't understand it!
How can I get the battery level?
Please can you give me the code and tell me, what I have to write, when I want to
play a sound, when I have a bad battery