fsincos

Sine and Cosine

FSINCOS

Computes sine and cosine of ST(0), pushing both to stack.

Details

Computes both sine and cosine of ST(0) in a single operation, pushing the cosine result onto the stack and leaving the sine in ST(0). The stack pointer is incremented after the push, so the sine ends up in ST(0) and cosine in ST(1). The x87 status flags are updated; C2 may be set if the argument is out of range.

Pseudocode Operation

temp ← ST(0); ST(0) ← sin(temp); push(cos(temp)); TOS ← TOS + 1

Example

FSINCOS

Encoding

Binary Layout
D9
+0
FB
+1
 
Format Legacy
Opcode D9 FB
Extension x87 FPU

Operands

Reference (Intel® SDM)

Instruction Forms

Opcode Instruction Op/En 64/32-bit Mode CPUID Description
D9 FB FSINCOS Valid Valid Compute the sine and cosine of ST(0); replace ST(0) with the approximate sine, and push the approximate cosine onto the register stack.

Description

Computes both the approximate 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 −263 to +263. The following table shows the results obtained when taking the sine and cosine of various classes of numbers, assuming that underflow does not occur. Table 3-38. FSINCOS Results 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

Operation

IF ST(0) < 263
THEN
C2 := 0;
TEMP := fcos(ST(0)); // approximation of cosine
ST(0) := fsin(ST(0)); // approximation of sine
TOP := TOP − 1;
ST(0) := TEMP;
ELSE (* Source operand out of range *)
C2 := 1;
FI;

Exceptions

Protected Mode Exceptions

#NM CR0.EM[bit 2] or CR0.TS[bit 3] = 1. #MF If there is a pending x87 FPU exception. #UD If the LOCK prefix is used.

Real-Address Mode Exceptions

Same exceptions as in protected mode.

Virtual-8086 Mode Exceptions

Same exceptions as in protected mode.

Compatibility Mode Exceptions

Same exceptions as in protected mode.

64-Bit Mode Exceptions

Same exceptions as in protected mode. FSINCOS—Sine and Cosine Vol. 2A 3-383