123 lines
1.8 KiB
ArmAsm
123 lines
1.8 KiB
ArmAsm
.global is_alpha, is_digit, is_alnum, write_out, read_file, exit
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.section .rodata
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.equ SYS_READ, 63
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.equ SYS_WRITE, 64
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.equ SYS_EXIT, 93
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.equ STDIN, 0
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.equ STDOUT, 1
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.equ STDERR, 2
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.section .text
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# Detects if the passed character is a 7-bit alpha character or an underscore.
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# The character is passed in a0.
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# Sets a0 to 1 if the character is an alpha character or underscore, sets it to 0 otherwise.
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.type is_alpha, @function
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is_alpha:
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li t0, 'A' - 1
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sltu t1, t0, a0 # t1 = a0 >= 'A'
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sltiu t2, a0, 'Z' + 1 # t2 = a0 <= 'Z'
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and t1, t1, t2 # t1 = a0 >= 'A' & a0 <= 'Z'
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li t0, 'a' - 1
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sltu t2, t0, a0 # t2 = a0 >= 'a'
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sltiu t3, a0, 'z' + 1 # t3 = a0 <= 'z'
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and t2, t2, t3 # t2 = a0 >= 'a' & a0 <= 'z'
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xori t3, a0, '_'
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seqz t3, t3
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or a0, t1, t2
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or a0, a0, t3
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ret
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.type is_digit, @function
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is_digit:
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li t0, '0' - 1
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sltu t1, t0, a0 # t1 = a0 >= '0'
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sltiu t2, a0, '9' + 1 # t2 = a0 <= '9'
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and a0, t1, t2
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ret
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.type is_alnum, @function
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is_alnum:
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# Prologue.
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addi sp, sp, -16
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sw ra, 12(sp)
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sw s0, 8(sp)
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addi s0, sp, 16
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sw a0, 4(sp)
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call is_alpha
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sw a0, 0(sp)
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lw a0, 4(sp)
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call is_digit
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lw a1, 0(sp)
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or a0, a0, a1
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# Epilogue.
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lw ra, 12(sp)
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lw s0, 8(sp)
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addi sp, sp, 16
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ret
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.type write, @function
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write_out:
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# Prologue.
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addi sp, sp, -8
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sw ra, 4(sp)
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sw s0, 0(sp)
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addi s0, sp, 8
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mv a2, a1
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mv a1, a0
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li a0, STDOUT
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li a7, SYS_WRITE
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ecall
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# Epilogue.
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lw ra, 4(sp)
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lw s0, 0(sp)
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addi sp, sp, 8
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ret
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# Reads standard input into a buffer.
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# a0 - Buffer pointer.
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# a1 - Buffer size.
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#
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# Returns the result in a0.
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.type read_file, @function
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read_file:
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# Prologue.
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addi sp, sp, -8
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sw ra, 4(sp)
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sw s0, 0(sp)
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addi s0, sp, 8
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mv a2, a1
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mv a1, a0
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li a0, STDIN
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li a7, SYS_READ
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ecall
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# Epilogue.
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lw ra, 4(sp)
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lw s0, 0(sp)
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addi sp, sp, 8
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ret
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# Terminates the program. a0 contains the return code.
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exit:
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li a7, SYS_EXIT
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ecall
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