296 lines
4.6 KiB
ArmAsm
296 lines
4.6 KiB
ArmAsm
.global _is_alpha, _is_digit, _is_alnum, _is_upper, _is_lower
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.global _write_out, _read_file, _memcmp, _write_error, _put_char, _printi
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.global _divide_by_zero_error, _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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new_line: .ascii "\n"
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.section .text
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# Write the current token to stderr.
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# a0 - String pointer.
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# a1 - String length.
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.type _write_error, @function
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_write_error:
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mv t0, a0
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mv t1, a1
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li a0, STDERR
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mv a1, t0
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mv a2, t1
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li a7, SYS_WRITE
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ecall
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li a0, STDERR
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la a1, new_line
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li a2, 1
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li a7, SYS_WRITE
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ecall
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ret
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# a0 - First pointer.
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# a1 - Second pointer.
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# a2 - The length to compare.
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#
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# Returns 0 in a0 if memory regions are equal.
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.type _memcmp, @function
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_memcmp:
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mv t0, a0
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li a0, 0
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.Lmemcmp_loop:
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beqz a2, .Lmemcmp_end
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lbu t1, (t0)
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lbu t2, (a1)
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sub a0, t1, t2
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bnez a0, .Lmemcmp_end
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addi t0, t0, 1
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addi a1, a1, 1
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addi a2, a2, -1
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j .Lmemcmp_loop
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.Lmemcmp_end:
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ret
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# Detects if a0 is an uppercase character. Sets a0 to 1 if so, otherwise to 0.
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.type _is_upper, @function
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_is_upper:
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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 a0, t1, t2 # t1 = a0 >= 'A' & a0 <= 'Z'
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ret
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# Detects if a0 is an lowercase character. Sets a0 to 1 if so, otherwise to 0.
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.type _is_lower, @function
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_is_lower:
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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 a0, t2, t3 # t2 = a0 >= 'a' & a0 <= 'z'
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ret
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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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# 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_upper
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sw a0, 0(sp)
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lw a0, 4(sp)
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call _is_lower
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lw t0, 4(sp)
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xori t1, t0, '_'
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seqz t1, t1
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lw t0, 0(sp)
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or a0, a0, t0
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or a0, a0, t1
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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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# Detects whether the passed character is a digit
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# (a value between 0 and 9).
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#
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# Parameters:
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# a0 - Exemined value.
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#
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# Sets a0 to 1 if it is a digit, to 0 otherwise.
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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_out, @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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#
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# Parameters:
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# a0 - Status code.
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.type _exit, @function
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_exit:
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li a7, SYS_EXIT
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ecall
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# ret
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.type _divide_by_zero_error, @function
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_divide_by_zero_error:
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addi a7, zero, 172 # getpid
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ecall
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addi a1, zero, 8 # SIGFPE
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addi a7, zero, 129 # kill
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ecall
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ret
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# a0 - Whole number.
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# t1 - Constant 10.
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# a1 - Local buffer.
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# t2 - Current character.
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# t3 - Whether the number is negative.
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.type printi, @function
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_printi:
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addi sp, sp, -16
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sw s0, 0(sp)
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sw ra, 4(sp)
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addi s0, sp, 16
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addi t1, zero, 10
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addi a1, s0, -1
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addi t3, zero, 0
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bge a0, zero, .digit10
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addi t3, zero, 1
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sub a0, zero, a0
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.digit10:
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rem t2, a0, t1
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addi t2, t2, '0'
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sb t2, 0(a1)
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div a0, a0, t1
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addi a1, a1, -1
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bne zero, a0, .digit10
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beq zero, t3, .write_call
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addi t2, zero, '-'
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sb t2, 0(a1)
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addi a1, a1, -1
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.write_call:
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addi a0, zero, 1
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addi a1, a1, 1
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sub a2, s0, a1
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addi a7, zero, 64 # write
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ecall
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lw s0, 0(sp)
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lw ra, 4(sp)
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addi sp, sp, 16
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ret
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# Writes a character from a0 into the standard output.
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.type _put_char, @function
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_put_char:
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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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sb a0, 4(sp)
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li a0, STDOUT
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addi a1, sp, 4
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li a2, 1
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li a7, SYS_WRITE
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ecall
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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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add sp, sp, 16
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ret
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