These options are defined for the MSP430:
__. This in turn will be used by the
msp430.hheader file to select an MCU specific supplimentary header file.
The option also sets the ISA to use. If the MCU name is one that is
known to only support the 430 ISA then that is selected, otherwise the
430X ISA is selected. A generic MCU name of
msp430 can also be
used to select the 430 ISA. Similarly the generic
name will select the 430X ISA.
In addition an MCU specific linker script will be added to the linker
command line. The script's name is the name of the MCU with
.ld appended. Thus specifying -mmcu=xxx on the gcc
command line will define the C preprocessor symbol
cause the linker to search for a script called xxx.ld.
This option is also passed on to the assembler.
msp430xv2. This option is deprecated. The -mmcu= option should be used to select the ISA.
nonefor no hardware multiply,
16bitfor the original 16-bit-only multiply supported by early MCUs.
32bitfor the 16/32-bit multiply supported by later MCUs and
f5seriesfor the 16/32-bit multiply supported by F5-series MCUs. A value of
autocan also be given. This tells GCC to deduce the hardware multiply support based upon the MCU name provided by the -mmcu option. If no -mmcu option is specified then
32bithardware multiply support is assumed.
autois the default setting.
Hardware multiplies are normally performed by calling a library
routine. This saves space in the generated code. When compiling at
-O3 or higher however the hardware multiplier is invoked
inline. This makes for bigger, but faster code.
The hardware multiply routines disable interrupts whilst running and restore the previous interrupt state when they finish. This makes them safe to use inside interrupt handlers as well as in normal code.