x86 Instruction Set Reference


Sine and Cosine

Opcode Mnemonic 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.

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.

FSINCOS results
Source: ST(0)Destination: ST(1) CosineDestination: ST(0) Sine
-F-1 to +1-1 to +1
+F-1 to +1-1 to +1
F Means finite floating-point value.
* 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-ofrange 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 2Pi or by using the FPREM instruction with a divisor of 2Pi. See the section titled "Pi" in Chapter 8 of the IA-32 Intel Architecture Software Developer's Manual, Volume 1, for a discussion of the proper value to use for pi in performing such reductions.

if(ST(0) < (1 << 63)) {
	C2 = 0;
	Temporary = Cosine(ST(0));
	ST(0) = Sine(ST(0));
	Top = Top - 1;
	ST(0) = Temporary;
else C2 = 1; //source operand out of range
FPU flags affected

C1 Set to 0 if stack underflow occurred; set to 1 of stack overflow occurs. Set if result was rounded up; cleared otherwise. C2 Set to 1 if outside range (-2^63 < source operand < +2^63); otherwise, set to 0. C0, C3 Undefined.

Floating-Point Exceptions
#ISStack underflow or overflow occurred.
#ISStack underflow or overflow occurred.
#IASource operand is an SNaN value, infinite, or unsupported format.
#DSource operand is a denormal value.
#UResult is too small for destination format.
Protected Mode Exceptions
#NMEM or TS in CR0 is set.
Real-Address Mode Exceptions
#NMEM or TS in CR0 is set.
Virtual-8086 Mode Exceptions
#NMEM or TS in CR0 is set.
Instruction Latency Throughput Execution Unit