Arm® A32/T32 Instruction Set Architecture: Armv8, for Armv8-A architecture profile Documentation

VRINTX (floating-point)

Round floating-point to integer inexact rounds a floating-point value to an integral floating-point value of the same size, using the rounding mode specified in the FPSCR, and raises an Inexact exception when the result value is not numerically equal to the input value. A zero input gives a zero result with the same sign, an infinite input gives an infinite result with the same sign, and a NaN is propagated as for normal arithmetic.

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

A1

if size == '00' || (size == '01' && !HaveFP16Ext()) then UNDEFINED;
if size == '01' && cond != '1110' then UNPREDICTABLE;
exact = TRUE;
case size of
    when '01' esize = 16; d = UInt(Vd:D); m = UInt(Vm:M);
    when '10' esize = 32; d = UInt(Vd:D); m = UInt(Vm:M);
    when '11' esize = 64; d = UInt(D:Vd); m = UInt(M:Vm);

T1

if size == '00' || (size == '01' && !HaveFP16Ext()) then UNDEFINED;
if size == '01' && InITBlock()  then UNPREDICTABLE;
exact = TRUE;
case size of
    when '01' esize = 16; d = UInt(Vd:D); m = UInt(Vm:M);
    when '10' esize = 32; d = UInt(Vd:D); m = UInt(Vm:M);
    when '11' esize = 64; d = UInt(D:Vd); m = UInt(M:Vm);

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

if ConditionPassed() then
    EncodingSpecificOperations(); CheckVFPEnabled(TRUE);
    rounding = FPRoundingMode(FPSCR[]);
    case esize of
        when 16
            S[d] = Zeros(16) : FPRoundInt(S[m]<15:0>, FPSCR[], rounding, exact);
        when 32
            S[d] = FPRoundInt(S[m], FPSCR[], rounding, exact);
        when 64
            D[d] = FPRoundInt(D[m], FPSCR[], rounding, exact);