STUMAX, STUMAXL

Atomic unsigned maximum on word or doubleword in memory, without return, atomically loads a 32-bit word or 64-bit doubleword from memory, compares it against the value held in a register, and stores the larger value back to memory, treating the values as unsigned numbers.

For information about memory accesses see Load/Store addressing modes.

This is an alias of LDUMAX, LDUMAXA, LDUMAXAL, LDUMAXL. This means:

Integer
(ARMv8.1)

313029282726252423222120191817161514131211109876543210
1x1110000R1Rs011000Rn11111
sizeAopcRt

32-bit LDUMAX alias (size == 10 && R == 0)

STUMAX <Ws>, [<Xn|SP>]

is equivalent to

LDUMAX <Ws>, WZR, [<Xn|SP>]

and is always the preferred disassembly.

32-bit LDUMAXL alias (size == 10 && R == 1)

STUMAXL <Ws>, [<Xn|SP>]

is equivalent to

LDUMAXL <Ws>, WZR, [<Xn|SP>]

and is always the preferred disassembly.

64-bit LDUMAX alias (size == 11 && R == 0)

STUMAX <Xs>, [<Xn|SP>]

is equivalent to

LDUMAX <Xs>, XZR, [<Xn|SP>]

and is always the preferred disassembly.

64-bit LDUMAXL alias (size == 11 && R == 1)

STUMAXL <Xs>, [<Xn|SP>]

is equivalent to

LDUMAXL <Xs>, XZR, [<Xn|SP>]

and is always the preferred disassembly.

Assembler Symbols

<Ws>

Is the 32-bit name of the general-purpose register holding the data value to be operated on with the contents of the memory location, encoded in the "Rs" field.

<Xs>

Is the 64-bit name of the general-purpose register holding the data value to be operated on with the contents of the memory location, encoded in the "Rs" field.

<Xn|SP>

Is the 64-bit name of the general-purpose base register or stack pointer, encoded in the "Rn" field.

Operation

The description of LDUMAX, LDUMAXA, LDUMAXAL, LDUMAXL gives the operational pseudocode for this instruction.


Internal version only: isa v27.02, AdvSIMD v26.0, pseudocode v34.2.2 ; Build timestamp: 2018-03-28T19:55

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