gencode.sh

a linux like c++ kernel

#!/bin/sh
cat <<\! > idletaskcode.S 
#include "../lib/unistd.h"
	.text
	.global _start
_start: movl $__NR_fork,%eax
	int $0x80
	cmpl $0,%eax
	jne 1f
	/* child process */
	movl $__NR_setup,%eax
	int $0x80
	movl $__NR_execve,%eax
	movl $path,%ebx
	movl $argv,%ecx
	movl $envp,%edx 
	int $0x80
1:	/* parent process */
	movl $__NR_nice,%eax
	int $0x80
	jmp 1b
path:	.asciz "/sbin/init"
arg0:	.asciz "init"
argv:	.long arg0,0
env0:	.asciz "bee=sparrow"
envp:	.long env0,0
!
cc -c -o idletaskcode.o idletaskcode.S
ld -Ttext 0x1000 idletaskcode.o -o idletaskcode

# readelf output format: Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
exec > idletaskcode.h
echo "/* this file is auto generated by gencode.sh */"
echo "#define IDLETASKSTART 0x1000 /* ld depend this */"
echo "#define IDLETASKEND 0x2000 /* ld depend this */"
offset=$(readelf --segments idletaskcode | awk '/LOAD/ { print $2; exit; }')
filesz=$(readelf --segments idletaskcode | awk '/LOAD/ { print $5; exit; }')
od --width=1 --output-duplicates --skip-bytes=$offset --read-bytes=$filesz \
-t x1 idletaskcode | awk '
BEGIN	{	tab = 0
		print "char idletaskcode[] = {"
	}
// 	{	if (NF == 2) {
			printf("0x%s, ",$2)
			if ((tab++ % 8) == 7)
				printf("\n")
		}
	}
END	{	print "};"
	}
'
rm -f idletaskcode.S idletaskcode.o idletaskcode