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in the Neuron Assembly language. The Neuron C compiler can optionally produce an
assembly listing, and examining this listing can help the programmer to optimize the Neuron
C source code. See the Neuron Assembly Language Reference for more information about the
processor instructions.
Table 8. Program Control Instructions
Instruction
Instruction
Size
(Bytes)
CPU
Cycles
Required Description
NOP 1 1 No operation
SBR 1 1 Short unconditional branch
Offset: 0 to 15.
BR
BRC
BRNC
2 2 Branch
Branch on carry
Branch on not carry
Offset: –128 to +127.
SBRZ
SBRNZ
1 3 Short branch on TOS zero
Short branch on TOS not zero
Offset: 0 to 15. Drops TOS.
BRF 3 4 Unconditional branch far
BRZ
BRNZ
2 4 Branch on TOS zero
Branch on TOS not zero
Offset: –128 to +127. Drops TOS.
RET 1 5 Return from subroutine.
Drops two bytes from return stack.
BRNEQ 3 4 / 6
(taken /
not taken)
Branch if TOS not equal
Offset: –128 to +127. Drops TOS if equal.
DBRNZ 2 5 Decrement [RSP] and branch if not zero
Offset: –128 to +127. If not taken, drops
one byte from return stack.
CALLR 2 5 Call subroutine relative
Offset: –128 to +127. Pushes two bytes to
return stack.
CALL 2 6 Call subroutine
Address in low 8 KB. Pushes two bytes to
return stack.
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