Zilog EZ80F916 - Manual (Page 81)

UM014423-0607 Using the Integrated Development Environment
ZiLOG Developer Studio II
eZ80Acclaim! ® User Manual
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Jump Optimization
When selected, the Jump Optimization check box allows the assembler to replace relative
jump instructions (JR and DJNZ) with absolute jump instructions when the target label is
either
•
outside of the +127 to –128 range
For example, when the target is out of range, the assembler changes
DJNZ r0, lab
to
DJNZ r0, lab1
JR lab2
lab1:JP lab
lab2:
•
external to the assembly file
When the target label is external to the assembly file, the assembler always assumes
that the target address is out of range.
It is usually preferable to allow the assembler to make these replacements because if the
target of the jump is out of range, the assembler would otherwise not be able to generate
correct code for the jump. However, if you are very concerned about monitoring the code
size of your assembled application, you can deselect the Jump Optimization check box.
You will then get an error message (from the assembler if the target label is in the same
assembly file or from the linker if it is not) every time the assembler is unable to reach the
target label with a relative jump. This might give you an opportunity to try to tune your
code for greater efficiency.
The default is checked.
Project Settings—Code Generation Page
NOTE: For Assembly Only projects, the Code Generation page is not available.
The following figure shows the Code Generation page.