Mitsubishi Q00CPU, Руководство пользователя

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APPENDICES
Appendix 5 Method of replacing High Performance model QCPU with Universal model QCPU
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(b) Replacing a part of floating-point operation instructions with double-
precision floating-point operation instructions
Only operations require high accuracy are replaced with double-precision floating-
point operation instructions. Using the ECON and EDCON instructions, convert
floating-point data mutually between single precision and double-precision. The
flow of a replacement program is as follows:
• Data required for operations are converted from single precision to double
precision using the ECON instruction.
• Operations are performed in double precision using the double-precision
floating-point operation instructions.
• Operation results are converted from double precision to single precision
using the EDCON instruction.
A program example that floating-point data are converted mutually between single
precision and double precision before and after operations is shown below.
Example) Replacing the floating-point operation [A B+C] (Using the
ECON and EDCON instructions)
1) Device assignment
2) Program before replacement
TableApp.76 Device assignment
Before replacement After replacement
Application Device Data type Application Device Data type
Data A D0 to D1
Floating-point
data (single
precision)
Data A D0 to D1
Floating-point
data (single
precision)
Data B D2 to D3 Data B D2 to D3
Data C D4 to D5 Data C D4 to D5
Operation
result
D6 to D7
Operation
result
D6 to D7
Data A (D) D10 to D13
Floating-point
data (double
precision)
Data B (D) D14 to D17
Data C (D) D18 to D21
Operation
result (D)
D22 to D25
Figure App.22 Sample program