learn_riscv/lowlevellearning/hello.s

.global _start
# let's us export an elf file so the linker can see it
_start:
    ### Invoking the Write syscalls ###
    # Check `man 2 write`
    # ssize_t write(int fd, const void *buf, size_t count)
    # stdout FD =1 by the way in standard linux
    # Setup syscall number in a7 to be the write syscall (which is 64)
    addi a7, zero, 64
    # put the file descriptor value into a0
    addi a0, zero, 1
    # We need to load into a1 the address of our helloworld label
    la a1, helloworld
    # Now we need to set the last argument to the string of the string we want to write
    addi a2, zero, 15
    ecall

    ### SYSTEM EXIT ###
    # Adding into a7 the number 93 which is syscall number for exit
    addi a7, zero, 93
    # check man exit `void exit(int status)`. We need to put into a0 the argument to exit syscall
    addi a0, zero, 13
    # invoke the syscall
    ecall


# This is a label called helloworld.
# The string is 15 bytes long since this is ascii
helloworld:
    .ascii "Hello, RISC V\n"