ARM Architecture Reference Manual ARMv7-A and ARMv7-R edition

A9.5.1 CHKA
ThumbEE
CHKA (Check Array) compares the unsigned values in two registers. If the first is lower than, or the same as,
the second, it copies the PC to the LR, and causes a branch to the IndexCheck handler.
Encoding E1 ThumbEE
CHKA ,
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
1 1 0 0 1 0 1 0 N Rm Rn
n = UInt(N:Rn); m = UInt(Rm);
if n == 15 || BadReg(m) then UNPREDICTABLE;
Assembler syntax
CHKA ,
where:
See Standard assembler syntax fields on page A8-7.
The first operand register. This contains the array size. Use of the SP is permitted.
The second operand register. This contains the array index.
Operation
if ConditionPassed() then
EncodingSpecificOperations();
if UInt(R[n])