VQRDMLSH

Vector Saturating Rounding Doubling Multiply Subtract Returning High Half. This instruction multiplies the vector elements of the first source SIMD&FP register with either the corresponding vector elements of the second source SIMD&FP register or the value of a vector element of the second source SIMD&FP register, without saturating the multiply results, doubles the results, and subtracts the most significant half of the final results from the vector elements of the destination SIMD&FP register. The results are rounded.

If any of the results overflow, they are saturated. The cumulative saturation bit, FPSCR.QC, is set if saturation occurs. For details see Pseudocode details of saturation.

Depending on settings in the CPACR, NSACR, and HCPTR registers, and the Security state and PE mode in which the instruction is executed, an attempt to execute the instruction might be undefined, or trapped to Hyp mode. For more information see Enabling Advanced SIMD and floating-point support.

It has encodings from the following instruction sets: A32 ( A1 and A2 ) and T32 ( T1 and T2 ) .

A1
(FEAT_RDM)

if !HaveQRDMLAHExt() then UNDEFINED; if Q == '1' && (Vd<0> == '1' || Vn<0> == '1' || Vm<0> == '1') then UNDEFINED; if size == '00' || size == '11' then UNDEFINED; add = FALSE; scalar_form = FALSE; esize = 8 << UInt(size); elements = 64 DIV esize; d = UInt(D:Vd); n = UInt(N:Vn); m = UInt(M:Vm); regs = if Q == '0' then 1 else 2; integer index = integer UNKNOWN;

A2
(FEAT_RDM)

if !HaveQRDMLAHExt() then UNDEFINED; if size == '11' then SEE "Related encodings"; if size == '00' then UNDEFINED; if Q == '1' && (Vd<0> == '1' || Vn<0> == '1') then UNDEFINED; add = FALSE; scalar_form = TRUE; d = UInt(D:Vd); n = UInt(N:Vn); regs = if Q == '0' then 1 else 2; integer esize; integer elements; integer m; integer index; if size == '01' then esize = 16; elements = 4; m = UInt(Vm<2:0>); index = UInt(M:Vm<3>); if size == '10' then esize = 32; elements = 2; m = UInt(Vm); index = UInt(M);

T1
(FEAT_RDM)

if !HaveQRDMLAHExt() then UNDEFINED; if InITBlock() then UNPREDICTABLE; if Q == '1' && (Vd<0> == '1' || Vn<0> == '1' || Vm<0> == '1') then UNDEFINED; if size == '00' || size == '11' then UNDEFINED; add = FALSE; scalar_form = FALSE; esize = 8 << UInt(size); elements = 64 DIV esize; d = UInt(D:Vd); n = UInt(N:Vn); m = UInt(M:Vm); regs = if Q == '0' then 1 else 2; integer index = integer UNKNOWN;

CONSTRAINED UNPREDICTABLE behavior

If InITBlock(), then one of the following behaviors must occur:

• The instruction is undefined.
• The instruction executes as if it passes the Condition code check.
• The instruction executes as NOP. This means it behaves as if it fails the Condition code check.

T2
(FEAT_RDM)

if !HaveQRDMLAHExt() then UNDEFINED; if InITBlock() then UNPREDICTABLE; if size == '11' then SEE "Related encodings"; if size == '00' then UNDEFINED; if Q == '1' && (Vd<0> == '1' || Vn<0> == '1') then UNDEFINED; add = FALSE; scalar_form = TRUE; d = UInt(D:Vd); n = UInt(N:Vn); regs = if Q == '0' then 1 else 2; integer esize; integer m; integer index; integer elements; if size == '01' then esize = 16; elements = 4; m = UInt(Vm<2:0>); index = UInt(M:Vm<3>); if size == '10' then esize = 32; elements = 2; m = UInt(Vm); index = UInt(M);

CONSTRAINED UNPREDICTABLE behavior

If InITBlock(), then one of the following behaviors must occur:

• The instruction is undefined.
• The instruction executes as if it passes the Condition code check.
• The instruction executes as NOP. This means it behaves as if it fails the Condition code check.

Assembler Symbols