Question

Write Nios II assembler instructions that will invert bits 3 to 0, set (turn on) bits 11 to 8 and reset (turn off) bits 31 to 12 in register r4. All other bits in r4 should be left unchanged. Finish off this piece of code with a jump immediate to address 0x00000040

Answer 1

L_PIN EQU 0
XOR temp,#0<<L_PIN ;invert bit 0
L_PIN EQU 1
XOR temp,#1<<L_PIN ;invert bit 1
L_PIN EQU 2
XOR temp,#2<<L_PIN ;invert bit 2
Setb acc.8 ;set bit 8
Setb acc.9 ;set bit 9
Setb acc.10 ;set bit 10
Setb acc.11 ;set bit 11
Btr acc.12 ;reset the bit 12
Btr acc.13 ;reset the bit 13
Btr acc.14 ;reset the bit 14
Btr acc.15 ;reset the bit 15
Btr acc.16 ;reset the bit 16
Btr acc.17 ;reset the bit 17
Btr acc.18 ;reset the bit 18
Btr acc.19 ;reset the bit 19
Btr acc.20 ;reset the bit 20
Btr acc.21 ;reset the bit 21
Btr acc.22 ;reset the bit 22
Btr acc.23 ;reset the bit 23
Btr acc.24 ;reset the bit 24
Btr acc.25 ;reset the bit 25
Btr acc.26 ;reset the bit 26
Btr acc.27 ;reset the bit 27
Btr acc.28 ;reset the bit 28
Btr acc.29 ;reset the bit 29
Btr acc.30 ;reset the bit 30
Btr acc.31 ;reset the bit 31
mov eax, 0x00000040
jmp eax ;jumo to address 0x00000040