Atmel CAVR-4 사용자 설명서
CAVR-4
Part 2. Compiler reference
Compiler options
201
*The most important difference between
-z2
and
-z3
is that at level 2, all non-static variables
will live during their entire scope.
A low level of optimization makes it relatively easy to follow the program flow in the
debugger, and, conversely, a high level of optimization makes it relatively hard.
debugger, and, conversely, a high level of optimization makes it relatively hard.
Note: The
-s
and
-z
options cannot be used at the same time.
To set the equivalent option in IAR Embedded Workbench, select
Project>Options>C/C++ Compiler>Code.
Project>Options>C/C++ Compiler>Code.
--zero_register
--zero_register
Enabling this option will make the compiler use register
R15
as zero register, that is
register
R15
is assumed to always contain zero.
This option can in some cases reduce the size of the generated code, especially in the
Large memory model. The option may be incompatible with the supplied runtime
libraries. The linker will issue a link-time error if any incompatibilities arise.
Large memory model. The option may be incompatible with the supplied runtime
libraries. The linker will issue a link-time error if any incompatibilities arise.
--64bit_doubles
--64bit_doubles
Use this option to force the compiler to use 64-bit doubles instead of 32-bit doubles
which is the default. For additional information, see Floating-point types, page 139.
which is the default. For additional information, see Floating-point types, page 139.
This option is related to the Target options in the General Options category in IAR
Embedded Workbench.
Embedded Workbench.
--64k_flash
--64k_flash
This option tells the compiler that the intended target processor does not have more than
64 Kbytes program flash memory (small flash), and that the AVR core therefore does
not have the
64 Kbytes program flash memory (small flash), and that the AVR core therefore does
not have the
RAMPZ
register or the
ELPM
instruction. This option can only be used
together with the
-v2
,
-v3
, and
-v4
processor options.
To set the equivalent option in IAR Embedded Workbench, select
Project>Options>General Options>Target (No RAMPZ register).
Project>Options>General Options>Target (No RAMPZ register).