# hello-world.S - ClaudeOS user-mode hello world application
# Assembled as flat binary, loaded at USER_CODE_START (0x08048000)
#
# Uses INT 0x80 system calls:
#   SYS_WRITE(1): EAX=1, EBX=fd, ECX=buf, EDX=len
#   SYS_EXIT(0):  EAX=0, EBX=code

.code32
.section .text
.globl _start
_start:
    /* SYS_WRITE(stdout, "Hello, World\n", 13) */
    movl $1, %eax           /* SYS_WRITE */
    movl $1, %ebx           /* fd = stdout */
    movl $msg, %ecx         /* buf = absolute address of message */
    movl $13, %edx          /* len = 13 */
    int $0x80

    /* SYS_EXIT(0) */
    movl $0, %eax           /* SYS_EXIT */
    movl $0, %ebx           /* exit code = 0 */
    int $0x80

    /* Safety: infinite loop (should never reach here) */
    jmp .

msg:
    .ascii "Hello, World\n"