Arm keyboard scanner Problems

Arm keyboard scanner-general Linux technology-Linux technology and application information. For more information, see the following. Ladies and gentlemen, arm U8 Key_Scan Function
RGPGDAT = rGPGDAT &(~ (1 <6) | (1 <2) | (1 <6) | (0 <2); // GPG6, 2 output 0
RGPEDAT = rGPEDAT &(~ (1 <13) | (1 <11) | (1 <13) | (1 <11); // GPE13, 11 output 0
If (rGPFDAT & (1 <0) = 0) return 16;
Else if (rGPFDAT & (1 <2) = 0) return 15;
Else if (rGPGDAT & (1 <3) = 0) return 14;
Else if (rGPGDAT & (1 <11) = 0) return 13;

RGPGDAT = rGPGDAT &(~ (1 <6) | (1 <2) | (0 <6) | (1 <2); // GPG6, 2 output 0
RGPEDAT = rGPEDAT &(~ (1 <13) | (1 <11) | (1 <13) | (1 <11); // GPE13, 11 output 0
If (rGPFDAT & (1 <0) = 0) return 11;
Else if (rGPFDAT & (1 <2) = 0) return 8;
Else if (rGPGDAT & (1 <3) = 0) return 5;
Else if (rGPGDAT & (1 <11) = 0) return 2;

RGPGDAT = rGPGDAT &(~ (1 <6) | (1 <2) | (1 <6) | (1 <2); // GPG6, 2 output 0
RGPEDAT = rGPEDAT &(~ (1 <13) | (1 <11) | (1 <13) | (0 <11); // GPE13, 11 output 0
If (rGPFDAT & (1 <0) = 0) return 10;
Else if (rGPFDAT & (1 <2) = 0) return 7;
Else if (rGPGDAT & (1 <3) = 0) return 4;
Else if (rGPGDAT & (1 <11) = 0) return 1;

RGPGDAT = rGPGDAT &(~ (1 <6) | (1 <2) | (1 <6) | (1 <2); // GPG6, 2 output 0
RGPEDAT = rGPEDAT &(~ (1 <13) | (1 <11) | (0 <13) | (1 <11); // GPE13, 11 output 0
If (rGPFDAT & (1 <0) = 0) return 12;
Else if (rGPFDAT & (1 <2) = 0) return 9;
Else if (rGPGDAT & (1 <3) = 0) return 6;
Else if (rGPGDAT & (1 <11) = 0) return 3;
Else return 0xff;
I haven't understood it for a long time. I hope someone can give me some advice.