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MATH COPROCESSING
11-6
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 11-5. 80C187 Constant Instructions
FLDZ Load + 0.1
FLD1 Load +1.0
FLDPI Load
FLDL2T Load log
2
10
FLDL2E Load log
2
e
FLDLG2 Load log
10
2
FLDLN2 Load log
e
2
Table 11-6. 80C187 Processor Control Instructions
FINIT/FNINIT Initialize processor FLDENV Load environment
FDISI/FNDISI Disable interrupts FSAVE/FNSAVE Save state
FENI/FNENI Enable interrupts FRSTOR Restore state
FLDCW Load control word FINCSTP Increment stack pointer
FSTCW/FNSTCW Store control word FDECSTP Decrement stack pointer
FSTSW/FNSTSW Store status word FFREE Free register
FCLEX/FNCLEX Clear exceptions FNOP No operation
FSTENV/FNSTENV Store environment FWAIT CPU wait