3-242
INSTRUCTION SET REFERENCE
FSINCOSĀSine and Cosine
Description
This instruction computes both the sine and the cosine of the source operand in register ST(0),
stores the sine in ST(0), and pushes the cosine onto the top of the FPU register stack. (This
instruction is faster than executing the FSIN and FCOS instructions in succession.)
The source operand must be given in radians and must be within the range
?
2
63
to +2
63
. The
following table shows the results obtained when taking the sine and cosine of various classes of
numbers, assuming that underflow does not occur.
NOTES:
FMeans finite-real number.
*Indicates floating-point invalid-arithmetic-operand (#IA) exception.
If the source operand is outside the acceptable range, the C2 flag in the FPU status word is set,
and the value in register ST(0) remains unchanged. The instruction does not raise an exception
when the source operand is out of range. It is up to the program to check the C2 flag for out-of-
range conditions. Source values outside the range
?
2
63
to +2
63
can be reduced to the range of the
instruction by subtracting an appropriate integer multiple of 2
?
or by using the FPREM instruc-
tion with a divisor of 2
?
. Refer to Section 7.5.8., Pi in Chapter 7, Floating-Point Unit of the Intel
Architecture Software DeveloperĀs Manual, Volume 1, for a discussion of the proper value to use
for
?
in performing such reductions.
Opcode
Instruction
Description
D9 FB
FSINCOS
Compute the sine and cosine of ST(0); replace ST(0) with
the sine, and push the cosine onto the register stack.
SRC
DEST
ST(0)
ST(1) Cosine
ST(0) Sine
??
*
*
?
F
?
1 to +1
?
1 to +1
?
0
+
1
?
0
+
0
+
1
+
0
+F
?
1 to +1
?
1 to +1
+
?
*
*
NaN
NaN
NaN
