| Getting Started with GCC-ERC32: C/C++ Compilation System for Mission Critical Spacecraft Applications | ||
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If you want to see the generated code, then use the option -Wa,-a. The first part (-Wa,) means pass the second part (-a) to the assembler. You could also use the object code dump utility erc-coff-objdump to disassemble the generated code. If you compiled using the debug option -g then the disassembled instructions will be annotated with symbolic references.
Here is an example where we generate a machine code listing.
Example 1-4. Generating a Machine Code Listing
$ erc-coff-gcc -Wa,-a hello.c -o hello GAS-ERC /tmp/cca00558.s page 1 1 .file "hello.c" 2 gcc2_compiled.: 3 __gnu_compiled_c: 4 .section .rodata,"r" 5 .align 8 6 .LC0: 7 0000 48656C6C .ascii "Hello world\12\0" 7 6F20776F 7 726C640A 7 00 8 000d 000000 .text 9 .align 4 10 .global main 11 .proc 04 12 main: 13 0000 9DE3BF98 save %sp,-104,%sp 14 0004 11000000 sethi %hi(.LC0),%o0 15 0008 40000000 call printf,0 16 000c 90122000 or %o0,%lo(.LC0),%o0 17 0010 81C7E008 ret 18 0014 81E80000 restore ...more output...
Here is another example using the object code dump utility.
Example 1-5. Output from objdump
$ erc-coff-objdump -d hello hello: file format coff-erc Disassembly of section .text: 02000000 <_stext>: 2000000: 10 80 05 8d b 2001634 <__start> 2000004: 01 00 00 00 nop 2000008: 01 00 00 00 nop 200000c: 01 00 00 00 nop 2000010: a1 48 00 00 rd %psr, %l0 2000014: 29 00 80 04 sethi 0x8004, %l4 2000018: 81 c5 22 dc jmp %l4 + 0x2dc 200001c: a6 10 20 0b mov 0xb, %l3 2000020: a1 48 00 00 rd %psr, %l0 2000024: 29 00 80 04 sethi 0x8004, %l4 2000028: 81 c5 22 dc jmp %l4 + 0x2dc 200002c: a6 10 20 04 mov 4, %l3 2000030: a1 48 00 00 rd %psr, %l0 ...lots of output...
You can see how big your program is using the size command. The sizes are in bytes. Note that the UNIX command ls -s gives you the size of the file rather than the size of the executable program.
Example 1-6. Using the size command
$ erc-coff-size hello.o
text data bss dec hex filename
48 0 0 48 30 hello.o
$ erc-coff-size hello
text data bss dec hex filename
12368 8 536 12912 3270 hello
$ The names "text", "data" and "bss" refer to program sections as follows.
The text section contains executable instructions
The data section contains program variables and other initialized data
The bss section contains program variables and other data initialized to zero
To get more detail you can use the object code dump program, and ask for headers.
Example 1-7. Using the Object Code Dump Program
$ erc-coff-objdump -h hello
hello: file format coff-erc
Sections:
Idx Name Size VMA LMA File off Algn
0 .init 00000118 00000000 00000000 00001000 2**3
CONTENTS, CODE, NEVER_LOAD
1 .text 00002c88 02000000 02000000 00002000 2**2
CONTENTS, ALLOC, LOAD, CODE
2 .rodata 000003c8 02002c88 02002c88 00004c88 2**3
CONTENTS, ALLOC, LOAD, READONLY
3 .data 00000008 02100000 02003050 00006000 2**3
CONTENTS, ALLOC, LOAD, DATA
4 .bss 00000218 02100010 02100010 00000000 2**3
ALLOC
5 .stab 00002610 00000000 00000000 00006008 2**2
CONTENTS, DEBUGGING, NEVER_LOAD
6 .stabstr 00002595 00000000 00000000 00008618 2**0
CONTENTS, DEBUGGING, NEVER_LOAD
$ By default, the compiler generates a program that will run on the standard target board (the Temic Starter Kit), or on the simulator. If you wish to run on the XGC monitor, or on some other board then you will need to specify the memory layout and other parameters. These topics are covered in Chapter 2.