64 lines
1.8 KiB
ArmAsm
64 lines
1.8 KiB
ArmAsm
.text # section declaration
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output: .byte 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x0A
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# we must export the entry point to the ELF linker or loader.
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# They convientionally recognize _start as their entry point.
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# Use ld -e main to override the default if you wish
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.global _start
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_start:
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loop:
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# Attempt to read a single byte from STDIN
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mov $1, %rdx # set the size of chars we want
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mov $input, %rsi # Where to put it
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mov $0, %rdi # Where are we reading from
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mov $0, %rax # the syscall number for read
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syscall # call the Kernel
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# If we didn't read any bytes jump to Done
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test %rax, %rax # check what we got
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jz Done # Got EOF call it done
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# Move our byte into registers for processing
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movb input, %al # load char
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movzx %al, %r12 # We have to zero extend it to use it
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movzx %al, %r13 # We have to zero extend it to use it
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# Break out the nibbles
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shr $4, %r12 # Purge the bottom 4 bits
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and $0xF, %r13 # Chop off all but the bottom 4 bits
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# add our base pointer
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add $output, %r12 # Use that as our index into our array
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add $output, %r13 # Use that as our index into our array
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# Print our first Hex
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mov $1, %rdx # set the size of chars we want
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mov %r12, %rsi # What we are writing
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mov $1, %rdi # Stdout File Descriptor
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mov $1, %rax # the syscall number for write
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syscall # call the Kernel
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# Print our second Hex
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mov $1, %rdx # set the size of chars we want
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mov %r13, %rsi # What we are writing
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mov $1, %rdi # Stdout File Descriptor
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mov $1, %rax # the syscall number for write
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syscall # call the Kernel
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jmp loop
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Done:
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# program completed Successfully
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mov $0, %rdi # All is well
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mov $60, %rax # put the exit syscall number in eax
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syscall # Call it a good day
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.data
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write_size = 2
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input:
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.byte write_size
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