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STBFMINNM, STBFMINNML -- A64

STBFMINNM, STBFMINNML

Atomic BFloat16 floating-point minimum number, without return

This instruction atomically loads a 16-bit value from memory, calculates the BFloat16 minimum number with the value held in a register, and stores the result back to memory.

This instruction:

For more information about memory ordering semantics, see Load-Acquire, Store-Release.

For information about addressing modes, see Load/Store addressing modes.

Floating-point
(FEAT_LSFE)

313029282726252423222120191817161514131211109876543210
001111000R1Rs111100Rn11111
sizeVRAo3opcRt

Encoding for the No memory ordering variant

Applies when (R == 0)

STBFMINNM <Hs>, [<Xn|SP>]

Encoding for the Release variant

Applies when (R == 1)

STBFMINNML <Hs>, [<Xn|SP>]

Decode for all variants of this encoding

if !IsFeatureImplemented(FEAT_LSFE) then EndOfDecode(Decode_UNDEF); end; let s : integer = UInt(Rs); let n : integer = UInt(Rn); let datasize : integer{} = 16; let acquire : boolean = FALSE; let release : boolean = R == '1'; let tagchecked : boolean = n != 31;

Assembler Symbols

<Hs>

Is the 16-bit name of the SIMD&FP 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

AArch64_CheckFPEnabled(); var address : bits(64); var value : bits(datasize); var data : bits(datasize); let accdesc : AccessDescriptor = CreateAccDescFPAtomicOp(MemAtomicOp_BFMINNM, acquire, release, tagchecked); value = V{datasize}(s); if n == 31 then CheckSPAlignment(); address = SP{64}(); else address = X{64}(n); end; let comparevalue : bits(datasize) = ARBITRARY : bits(datasize); // Irrelevant when not executing CAS data = MemAtomic{datasize}(address, comparevalue, value, accdesc);


2026-03_rel 2026-03-26 20:48:11

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