NASM code for writing the integer in eax to stdout.

   1  
   2  segment .bss
   3          writeTemp       resb    10
   4  
   5  segment .text
   6  _writeln:                               
   7          MOV     ebx,    eax             ; Number is already in eax
   8          MOV     ecx,    10
   9          XOR     edi,    edi
  10  L0:
  11          CMP     eax,    0
  12          JE      L1
  13          ADD     edi,    1
  14          XOR     edx,    edx
  15          IDIV    ecx
  16          JMP     L0
  17  L1:
  18          ADD     edi,    writeTemp       ; Length of the number is in edi
  19          MOV     esi,    edi
  20          MOV byte        [edi],  10      ; Add a newline
  21          SUB     edi,    1
  22          XOR     eax,    eax
  23  L2:                             
  24          CMP     ebx,    0
  25          JE      L3
  26          MOV     eax,    ebx
  27          XOR     edx,    edx
  28          IDIV    ecx
  29          ADD     dl,     48
  30          MOV     [edi],  dl
  31          SUB     edi,    1
  32          MOV     ebx,    eax
  33          JMP     L2                      ; Number has been written to writeTemp from tail to head
  34  L3:                             
  35          MOV     eax,    4
  36          MOV     ebx,    1
  37          MOV     ecx,    writeTemp
  38          MOV     edx,    esi
  39          SUB     edx,    writeTemp
  40          ADD     edx,    1
  41          INT     80h

A simple automated GNU Makefile to build and link c/c++/asm projects. All the variables that need to be tweaked are located at the begining:
PROGNAME: the name of the executable to be built
CC: the C compiler
CPP: the C++ compiler
ASM: the assambler
LD: the linker

This searches for all *.c, *.cpp and *.s files and compiles them into objects. It then links all the files into a single executable.

The strip rule is used to strip all unwanted symbols from the resulting executable. This usually results in a significant (think 40%) size optimisation.

   1  
   2  $(VERBOSE).SILENT:
   3  
   4  PROGNAME = prog
   5  
   6  CC = gcc
   7  CC += -c
   8  CPP = g++
   9  CPP += -c
  10  ASM = nasm
  11  ASM += -f elf -d ELF_TYPE
  12  LD = g++
  13  
  14  OBJFILES = $(patsubst %.c,%.o,$(wildcard *.c))
  15  OBJFILES += $(patsubst %.s,%.o,$(wildcard *.s))
  16  OBJFILES += $(patsubst %.cpp,%.o,$(wildcard *.cpp))
  17  
  18  all: $(PROGNAME)
  19  
  20  clean:
  21  	@echo "Cleaning object files"
  22  	@echo "    rm -f     *.o"
  23  	rm -f *.o
  24  	@echo "Cleaning backups"
  25  	@echo "    rm -f     *~"
  26  	rm -f *~
  27  	@echo "Removing programme"
  28  	@echo "    rm -f     "$(PROGNAME)
  29  	rm -f $(PROGNAME)
  30  
  31  %.o: %.s
  32  	@echo "Assambling "$@
  33  	@echo "    ASM       "$<
  34  	$(ASM) $<
  35  
  36  %.o: %.c
  37  	@echo "Compiling "$@
  38  	@echo "    CC        "$<
  39  	$(CC) $<
  40  
  41  %.o: %.cpp
  42  	@echo "Compiling "$@
  43  	@echo "    CPP       "$<
  44  	$(CPP) $<
  45  
  46  $(PROGNAME): $(OBJFILES)
  47  	@echo "Linking "$@
  48  	@echo "    LD        -o "$(PROGNAME)"        "$(OBJFILES)
  49  	$(LD) -o $(PROGNAME) $(OBJFILES)
  50  
  51  strip: $(PROGNAME)
  52  	@echo "Stripping "$(PROGNAME)
  53  	echo -n "Size of "$(PROGNAME)" before strip is "
  54  	ls -sh $(PROGNAME) | cut -d' ' -f1
  55  	@echo "    strip     "$(PROGNAME)
  56  	strip $(PROGNAME)
  57  	echo -n "Size of "$(PROGNAME)" after strip is "
  58  	ls -sh $(PROGNAME) | cut -d' ' -f1
  59  
  60  nothing:
  61  	@echo "Nothing to do; quitting  :("
  62  	@echo "HINT: Try make all"
  63