MC68LC040RC25A Datasheet, PDF (10/442 Pages) Freescale Semiconductor, Inc – M68040 Users Manual

Freescale Semiconductor, Inc.
TABLE OF CONTENTS (Continued)
Paragraph
Number
Title
Page
Number
8.4.6.5
8.4.6.6
8.4.6.7
Write-Back Address and Write-Back Data ..................................... 8-26
Push Data ...................................................................................... 8-27
Access Error Stack Frame Return From Exception ....................... 8-27
9.1
9.2
9.2.1
9.2.2
9.2.2.1
9.2.2.2
9.2.3
9.2.3.1
9.2.3.2
9.2.3.3
9.2.3.4
9.2.4
9.3
9.4
9.4.1
9.4.2
9.5
9.5.1
9.5.2
9.6
9.6.1
9.6.2
9.7
9.7.1
9.7.1.1
9.7.1.2
9.7.2
9.7.2.1
9.7.2.2
9.7.3
9.7.3.1
9.7.3.2
9.7.4
9.7.4.1
9.7.4.2
Section 9
Floating-Point Unit (MC68040 Only)
Floating-Point Unit Pipeline ...................................................................9-1
Floating-Point User Programming Model .............................................. 9-2
Floating-Point Data Registers (FP7–FP0) ......................................... 9-2
Floating-Point Control Register (FPCR) ............................................ 9-3
Exception Enable Byte ...................................................................9-3
Mode Control Byte .........................................................................9-3
Floating-Point Status Register (FPSR) ..............................................9-4
Floating-Point Condition Code Byte............................................... 9-4
Quotient Byte .................................................................................9-5
Exception Status Byte ................................ .................................... 9-5
Accrued Exception (AEXC) Byte. .................................................. 9-5
Floating-Point Instruction Address Register (FPIAR) ........................ 9-6
Floating-Point Data Formats and Data Types....................................... 9-7
Computational Accuracy ....................................................................... 9-11
Intermediate Result ........................................................................... 9-12
Rounding the Result .......................................................................... 9-13
Postprocessing Operation..................................................................... 9-15
Underflow, Round, Overflow ............................................................. 9-16
Conditional Testing ............................................................................9-16
Floating-Point Exceptions ..................................................................... 9-20
Unimplemented Floating-Point Instructions....................................... 9-20
Unsupported Floating-Point Data Types ...........................................9-22
Floating-Point Arithmetic Exceptions ....................................................9-24
Branch/Set on Unordered (BSUN) ....................................................9-25
Maskable Exception Conditions ..................................................... 9-26
Nonmaskable Exception Conditions .............................................. 9-27
Signaling Not-a-Number (SNAN)....................................................... 9-27
Maskable Exception Conditions ..................................................... 9-27
Nonmaskable Exception Conditions .............................................. 9-27
Operand Error ................................................................................... 9-28
Maskable Exception Conditions ..................................................... 9-29
Nonmaskable Exception Conditions .............................................. 9-30
Overflow ............................................................................................ 9-31
Maskable Exception Conditions ..................................................... 9-31
Nonmaskable Exception Conditions .............................................. 9-31
xii
M68040 USER’S MANUAL
MOTOROLA
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