Constant Instructions; Processor Control Instructions; C187 Constant Instructions; C187 Processor Control Instructions - Intel 80C186XL User Manual

MATH COPROCESSING
11.3.1.5

Constant Instructions

Each constant instruction (see Table 11-5) loads a commonly used constant onto the stack. The
values have full 80-bit precision and are accurate to about 19 decimal digits. Since a temporary
real constant occupies 10 memory bytes, the constant instructions, only 2 bytes long, save mem-
ory space.
11.3.1.6

Processor Control Instructions

Computations do not use the processor control instructions; these instructions are available for
activities at the operating system level. This group (see Table 11-6) includes initialization, excep-
tion handling and task switching instructions.
Table 11-6. 80C187 Processor Control Instructions
FINIT/FNINIT
FDISI/FNDISI
FENI/FNENI
FLDCW
FSTCW/FNSTCW
FSTSW/FNSTSW
FCLEX/FNCLEX
FSTENV/FNSTENV
11-6
Table 11-5. 80C187 Constant Instructions
FLDZ Load + 0.1
FLD1 Load +1.0
FLDPI Load
FLDL2T Load log
2
FLDL2E Load log
2
FLDLG2 Load log
10
FLDLN2 Load log
e
Initialize processor
Disable interrupts
Enable interrupts
Load control word
Store control word
Store status word
Clear exceptions
Store environment
10
e
2
2
FLDENV Load environment
FSAVE/FNSAVE Save state
FRSTOR Restore state
FINCSTP Increment stack pointer
FDECSTP Decrement stack pointer
FFREE Free register
FNOP No operation
FWAIT CPU wait