x86 Opcode PFRCP

Opcode PFRCP

CPU: AMD-3D
Type of Instruction: User

Instruction: PFRCP dest,src

Description:

dest[31..0] <- Reciprocal(src[31..0]);
dest[63..32] <- Reciprocal(src[63..32]);

Note:
Newton-Raphson algorithm:

Division
----------

q = a/b;

X(i+1) = X(i) * (2 - b * X(i));

X0 = RFRCP(b);
X1 = RFRCPIT1(b,X0);
X2 = RFRCPIT2(X1,X0);
q = PFMUL(a,X2);

Square Root
--------------

X(i+1) = 1/2 * X(i) * (3 - b * X(i)^2);

X0 = PFRSQRT(b);
X1 = PFMUL(X0,X0);
X2 = PFRSQIT(b,X1);
X3 = PFRCPIT2(X2,X0);
X4 = PFMUL(b,X3);

Flags Affected: None

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COP & Times:

PFRCP mm,mm/m64 0FH 0FH 96H Postbyte