SDCC
3.2 Command Line Options
3.2.1 Processor Selection Options
-mmcs51 Generate code for the Intel MCS51 family of processors. This is the default processor target.
3.2.2 Preprocessor Options
SDCC uses an adapted version of the GNU Compiler Collection preprocessor cpp (gcc http://gcc.gnu.
org/). If you need more dedicated options than those listed below please refer to the GCC CPP Manual at
http://www.gnu.org/software/gcc/onlinedocs/.
-I<path> The additional location where the preprocessor will look for <..h> or “..h” files.
-D<macro[=value]> Command line definition of macros. Passed to the preprocessor.
-M Tell the preprocessor to output a rule suitable for make describing the dependencies of each object file.
For each source file, the preprocessor outputs one make-rule whose target is the object file name for
that source file and whose dependencies are all the files ‘#include’d in it. This rule may be a single line
or may be continued with ‘\’-newline if it is long. The list of rules is printed on standard output instead
of the preprocessed C program. ‘-M’ implies ‘-E’.
-C Tell the preprocessor not to discard comments. Used with the ‘-E’ option.
-MM Like ‘-M’ but the output mentions only the user header files included with ‘#include “file"’. System
header files included with ‘#include <file>’ are omitted.
-Aquestion(answer) Assert the answer answer for question, in case it is tested with a preprocessor conditional
such as ‘#if #question(answer)’. ‘-A-’ disables the standard assertions that normally describe the target
machine.
-Umacro Undefine macro macro. ‘-U’ options are evaluated after all ‘-D’ options, but before any ‘-include’ and
‘-imacros’ options.
-dM Tell the preprocessor to output only a list of the macro definitions that are in effect at the end of
preprocessing. Used with the ‘-E’ option.
-dD Tell the preprocessor to pass all macro definitions into the output, in their proper sequence in the rest
of the output.
-dN Like ‘-dD’ except that the macro arguments and contents are omitted. Only ‘#define name’ is included
in the output.
-pedantic-parse-number Pedantic parse numbers so that situations like 0xfe-LO_B(3) are parsed properly and the
macro LO_B(3) gets expanded. See also #pragma pedantic_parse_number on page 60 in section3.19
Note: this functionality is not in conformance with C99 standard!
-Wp preprocessorOption[,preprocessorOption]... Pass the preprocessorOption to the preprocessor sdcpp.
3.2.3 Linker Options
-L --lib-path <absolute path to additional libraries> This option is passed to the linkage editor’s additional libraries
search path. The path name must be absolute. Additional library files may be specified in the command
line. See section Compiling programs for more details.
--xram-loc <Value> The start location of the external ram, default value is 0. The value entered can be in Hexadecimal
or Decimal format, e.g.: --xram-loc 0x8000 or --xram-loc 32768.
--code-loc <Value> The start location of the code segment, default value 0. Note when this option is used the
interrupt vector table is also relocated to the given address. The value entered can be in Hexadecimal
or Decimal format, e.g.: --code-loc 0x8000 or --code-loc 32768.
--stack-loc <Value> By default the stack is placed after the data segment. Using this option the stack can be
placed anywhere in the internal memory space of the 8051. The value entered can be in Hexadecimal
or Decimal format, e.g. --stack-loc 0x20 or --stack-loc 32. Since the sp register is incremented before
a push or call, the initial sp will be set to one byte prior the provided value. The provided value should
not overlap any other memory areas such as used register banks or the data segment and with enough
space for the current application. The --pack-iram option (which is now a default setting) will override
this setting, so you should also specify the --no-pack-iram option if you need to manually place the
stack.
--xstack-loc <Value> By default the external stack is placed after the pdata segment. Using this option the xstack
can be placed anywhere in the external memory space of the 8051. The value entered can be in
Hexadecimal or Decimal format, e.g. --xstack-loc 0x8000 or --stack-loc 32768. The provided value
should not overlap any other memory areas such as the pdata or xdata segment and with enough space
for the current application.
--data-loc <Value> The start location of the internal ram data segment. The value entered can be in Hexadecimal
or Decimal format, eg. --data-loc 0x20 or --data-loc 32. (By default, the start location of the internal
ram data segment is set as low as possible in memory, taking into account the used register banks and
the bit segment at address 0x20. For example if register banks 0 and 1 are used without bit variables,
the data segment will be set, if --data-loc is not used, to location 0x10.)
--idata-loc <Value> The start location of the indirectly addressable internal ram of the 8051, default value is 0x80.
The value entered can be in Hexadecimal or Decimal format, eg. --idata-loc 0x88 or --idata-loc 136.
--bit-loc <Value> The start location of the bit addressable internal ram of the 8051. This is not implemented yet.
Instead an option can be passed directly to the linker: -Wl -bBSEG=<Value>.
--out-fmt-ihx The linker output (final object code) is in Intel Hex format. This is the default option. The format
itself is documented in the documentation of srecord.
--out-fmt-s19 The linker output (final object code) is in Motorola S19 format. The format itself is documented in
the documentation of srecord.
--out-fmt-elf The linker output (final object code) is in ELF format. (Currently only supported for the HC08 and
S08 processors)
-Wl linkOption[,linkOption]... Pass the linkOption to the linker. If a bootloader is used an option like ”-Wl -
bCSEG=0x1000” would be typical to set the start of the code segment. Either use the double quotes
around this option or use no space (e.g. -Wl-bCSEG=0x1000). See also #pragma constseg and
#pragma codeseg in section3.19. File sdcc/sdas/doc/asxhtm.html has more on linker options.
3.2.4 MCS51 Options
--model-small Generate code for Small model programs, see section Memory Models for more details. This is the
default model.
--model-medium Generate code for Medium model programs, see section Memory Models for more details. If
this option is used all source files in the project have to be compiled with this option. It must also be
used when invoking the linker.
--model-large Generate code for Large model programs, see section Memory Models for more details. If this
option is used all source files in the project have to be compiled with this option. It must also be used
when invoking the linker.
--model-huge Generate code for Huge model programs, see section Memory Models for more details. If this
option is used all source files in the project have to be compiled with this option. It must also be used
when invoking the linker.
--xstack Uses a pseudo stack in the pdata area (usually the first 256 bytes in the external ram) for allocating
variables and passing parameters. See section 3.18.1.2 External Stack for more details.
--iram-size <Value> Causes the linker to check if the internal ram usage is within limits of the given value.
--xram-size <Value> Causes the linker to check if the external ram usage is within limits of the given value.
--code-size <Value> Causes the linker to check if the code memory usage is within limits of the given value.
--stack-size <Value> Causes the linker to check if there is at minimum <Value> bytes for stack.
--pack-iram Causes the linker to use unused register banks for data variables and pack data, idata and stack
together. This is the default and this option will probably be removed along with the removal of --nopack-
iram.
--no-pack-iram (deprecated) Causes the linker to use old style for allocating memory areas. This option is now
deprecated and will be removed in future versions.
--acall-ajmp Replaces the three byte instructions lcall/ljmp with the two byte instructions acall/ajmp. Only use
this option if your code is in the same 2k block of memory. You may need to use this option for some
8051 derivatives which lack the lcall/ljmp instructions..