long print(const void *buf, long count) { #if defined(__x86_64__) asm volatile ( "syscall" : : "a"(1), "D"(1), "S"(buf), "d"(count) // RDI, RSI, RDX are used in x86-64 for write args : "rcx", "r11", "memory" ); #elif defined(__aarch64__) asm ( "mov x0, #1\n" // Move the exit status into register x0 "mov x1, %0\n" // Syscall number for 'exit' is 93 in AArch64 "mov x2, %1\n" // Syscall number for 'exit' is 93 in AArch64 "mov x8, #64\n" // Syscall number for 'exit' is 93 in AArch64 "svc #0\n" // Make the syscall : // No output operands : "r" (buf), "r"(count) // Input operand: status : "x0", "x8" // Clobbered registers ); #elif defined(__mips__) asm ( "li $a0, 1\n" "move $a1, %0\n" "move $a2, %1\n" "li $v0, 4004\n" "syscall" : : "r"(buf), "r"(count) : "a0", "a1", "a2", "v0" //TODO: temp registers clobbered by syscall should probably also be listed but this fn returns right away so it should be fine? ); #endif return 0; } void exit(int status) { #if defined(__x86_64__) asm volatile( "syscall" : : "a"(60), "D"(status) : ); #elif defined(__aarch64__) asm ( "mov x0, %0\n" // Move the exit status into register x0 "mov x8, #93\n" // Syscall number for 'exit' is 93 in AArch64 "svc #0\n" // Make the syscall : // No output operands : "r" ((long)status) // Input operand: status : "x0", "x8" // Clobbered registers ); #elif defined(__mips__) asm ( "move $a0, %0\n" "li $v0, 4001\n" "syscall" : : "r" (status) : "a0", "v0" ); #endif for(;;); } int main() { //void _start() { char *msg = "Hello World!\n"; print(msg, 13); return 69; } void __libc_start_main() {exit(main());} void _start() { __libc_start_main(); } void __start() { _start(); } /* #if defined(__x86_64__) printf("Compiled for x86_64 architecture\n"); #elif defined(__i386__) printf("Compiled for x86 architecture\n"); #elif defined(__arm__) printf("Compiled for ARM architecture\n"); #elif defined(__aarch64__) printf("Compiled for ARM64 architecture\n"); #elif defined(__mips__) printf("Compiled for ARM architecture\n"); #else printf("Unknown architecture\n"); #endif */