Intel ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS VOLUME 3 REV 2.3, Руководство пользователя

Страница: 1453 / 1898

Volume 4: Base IA-32 Instruction Reference 4:151
FPREM—Partial Remainder
Description
Computes the remainder obtained on dividing the value in the ST(0) register (the
dividend) by the value in the ST(1) register (the divisor or
modulus ), and stores the
result in ST(0). The remainder represents the following value:
Remainder = ST(0)  (N  ST(1))
Here, N is an integer value that is obtained by truncating the real-number quotient of
[ST(0) / ST(1)] toward zero. The sign of the remainder is the same as the sign of the
dividend. The magnitude of the remainder is less than that of the modulus, unless a
partial remainder was computed (as described below).
This instruction produces an exact result; the precision (inexact) exception does not
occur and the rounding control has no effect. The following table shows the results
obtained when computing the remainder of various classes of numbers, assuming that
underflow does not occur.
Notes:
Fmeans finite-real number.
*indicates floating-point invalid-arithmetic-operand (#IA) exception.
**indicates floating-point zero-divide (#Z) exception.
When the result is 0, its sign is the same as that of the dividend. When the modulus is
 , the result is equal to the value in ST(0).
The FPREM instruction does not compute the remainder specified in IEEE Std. 754. The
IEEE specified remainder can be computed with the FPREM1 instruction. The FPREM
instruction is provided for compatibility with the Intel 8087 and Intel287 math
coprocessors.
Opcode Instruction Description
D9 F8 FPREM Replace ST(0) with the remainder obtained on dividing ST(0)
by ST(1)
Table 2-7. FPREM Zeros and NaNs
ST(1)
-•

F

0 +0 +F +

NaN
-• * * * * * * NaN
ST(0)

F ST(0)

F or

0 ** **

F or

0 ST(0) NaN

0

0

0 * *

0

0 NaN
+0 +0 +0 * * +0 +0 NaN
+F ST(0) +F or +0 ** ** +F or +0 ST(0) NaN
+

* * * * * * NaN
NaN NaN NaN NaN NaN NaN NaN NaN