FCMGT (register)

Floating-point Compare Greater than (vector). This instruction reads each floating-point value in the first source SIMD&FP register and if the value is greater than the corresponding floating-point value in the second source SIMD&FP register sets every bit of the corresponding vector element in the destination SIMD&FP register to one, otherwise sets every bit of the corresponding vector element in the destination SIMD&FP register to zero.

This instruction can generate a floating-point exception. Depending on the settings in FPCR, the exception results in either a flag being set in FPSR, or a synchronous exception being generated. For more information, see Floating-point exception traps.

Depending on the settings in the CPACR_EL1, CPTR_EL2, and CPTR_EL3 registers, and the current Security state and Exception level, an attempt to execute the instruction might be trapped.

It has encodings from 4 classes: Scalar half precision , Scalar single-precision and double-precision , Vector half precision and Vector single-precision and double-precision

Scalar half precision
(FEAT_FP16)

if !HaveFP16Ext() then UNDEFINED; integer d = UInt(Rd); integer n = UInt(Rn); integer m = UInt(Rm); integer esize = 16; integer datasize = esize; integer elements = 1; CompareOp cmp; boolean abs; case E:U:ac of when '000' cmp = CompareOp_EQ; abs = FALSE; when '010' cmp = CompareOp_GE; abs = FALSE; when '011' cmp = CompareOp_GE; abs = TRUE; when '110' cmp = CompareOp_GT; abs = FALSE; when '111' cmp = CompareOp_GT; abs = TRUE; otherwise UNDEFINED;

Scalar single-precision and double-precision

integer d = UInt(Rd); integer n = UInt(Rn); integer m = UInt(Rm); integer esize = 32 << UInt(sz); integer datasize = esize; integer elements = 1; CompareOp cmp; boolean abs; case E:U:ac of when '000' cmp = CompareOp_EQ; abs = FALSE; when '010' cmp = CompareOp_GE; abs = FALSE; when '011' cmp = CompareOp_GE; abs = TRUE; when '110' cmp = CompareOp_GT; abs = FALSE; when '111' cmp = CompareOp_GT; abs = TRUE; otherwise UNDEFINED;

Vector half precision
(FEAT_FP16)

if !HaveFP16Ext() then UNDEFINED; integer d = UInt(Rd); integer n = UInt(Rn); integer m = UInt(Rm); integer esize = 16; integer datasize = if Q == '1' then 128 else 64; integer elements = datasize DIV esize; CompareOp cmp; boolean abs; case E:U:ac of when '000' cmp = CompareOp_EQ; abs = FALSE; when '010' cmp = CompareOp_GE; abs = FALSE; when '011' cmp = CompareOp_GE; abs = TRUE; when '110' cmp = CompareOp_GT; abs = FALSE; when '111' cmp = CompareOp_GT; abs = TRUE; otherwise UNDEFINED;

Vector single-precision and double-precision

integer d = UInt(Rd); integer n = UInt(Rn); integer m = UInt(Rm); if sz:Q == '10' then UNDEFINED; integer esize = 32 << UInt(sz); integer datasize = if Q == '1' then 128 else 64; integer elements = datasize DIV esize; CompareOp cmp; boolean abs; case E:U:ac of when '000' cmp = CompareOp_EQ; abs = FALSE; when '010' cmp = CompareOp_GE; abs = FALSE; when '011' cmp = CompareOp_GE; abs = TRUE; when '110' cmp = CompareOp_GT; abs = FALSE; when '111' cmp = CompareOp_GT; abs = TRUE; otherwise UNDEFINED;