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5 changed files with 441 additions and 224 deletions
+2
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@@ -16,6 +16,8 @@ Run the `make` command in the root of the repository.
Options:
`-b, --number-nonblank` - number nonempty output lines, overrides -n
`-E, --show-ends` - display $ at end of each line\
`-n, --number` - number all output lines
`--help` - Show the help page.\
`--version` - Show the version page.
+152
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@@ -0,0 +1,152 @@
.data
mod_buf_0: .space 36864
mod_buf_1: .space 36864
.section .text
.globl cat_file, open_fd
# Cat out the given file to stdout
# @param[in] a0: ptr to null-terminated file str. 0 = stdin
# @param[out] a0: result code.
cat_file:
addi sp, sp, -32
sd s0, 0(sp)
sd ra, 8(sp)
sd s1, 16(sp) # next modbuf to WRITE TO (inverse is read) 0=modbuf_0, 1=modbuf_1
sd s2, 24(sp) # current modbuf byte count
mv a1, a0 # since the function takes in a0, move it to a1 for syscall
li s1, 1
li s2, 0
beqz a0, 1f
call open_fd
j 2f
1:
li s0, 0 # stdin fd
2:
mv s0, a1 # put fd in s0
beqz a0, .LReadFileBlock # if we don't have an error, jump to reading
li a0, 1
j .LCatFileRet
.LReadFileBlock:
mv a0, s0
la a1, mod_buf_0
li a2, 4096
li a7, 63
ecall
blez a0, .LCloseFD # if we haven't read any bytes, EOF, close FD
mv s2, a0
li s1, 1
la t1, number_nonblank
lb t1, 0(t1)
beqz t1, .LNoNonblankNumbers
mv a1, s2 # load mod buf size to a1
beqz s1, 1f
la a0, mod_buf_0 # load mod_buf_0 as read buf
la a2, mod_buf_1 # load mod_buf_1 as write buf
j 2f
1:
la a0, mod_buf_1 # load mod_buf_1 as read buf
la a2, mod_buf_0 # load mod_buf_0 as write buf
2:
call add_line_numbers
xori s1, s1, 1 # flip the mod buf to write to
mv s2, a1 # update the current byte count
j .LNoNumbers # -n and -b are exclusive
.LNoNonblankNumbers:
la t1, number
lb t1, 0(t1)
beqz t1, .LNoNumbers
mv a1, s2 # load mod buf size to a1
beqz s1, 1f
la a0, mod_buf_0 # load mod_buf_0 as read buf
la a2, mod_buf_1 # load mod_buf_1 as write buf
j 2f
1:
la a0, mod_buf_1 # load mod_buf_1 as read buf
la a2, mod_buf_0 # load mod_buf_0 as write buf
2:
call add_line_numbers
xori s1, s1, 1 # flip the mod buf to write to
mv s2, a1 # update the current byte count
.LNoNumbers:
la t1, show_ends
lb t1, 0(t1)
beqz t1, .LNoEndings
mv a1, s2 # load mod buf size to a1
beqz s1, 1f
la a0, mod_buf_0 # load mod_buf_0 as read buf
la a2, mod_buf_1 # load mod_buf_1 as write buf
j 2f
1:
la a0, mod_buf_1 # load mod_buf_1 as read buf
la a2, mod_buf_0 # load mod_buf_0 as write buf
2:
call add_endings
xori s1, s1, 1 # flip the mod buf to write to
mv s2, a1 # update the current byte count
.LNoEndings:
beqz s1, 1f
la a1, mod_buf_0
j 2f
1:
la a1, mod_buf_1
2:
mv a2, s2 # load the amount of bytes read in previous step into bytes needed to write
li a0, 1
li a7, 64
ecall
j .LReadFileBlock
.LCloseFD:
mv a0, s0
li a7, 57 # close fd
ecall
.LCatFileRet:
ld s0, 0(sp)
ld ra, 8(sp)
ld s1, 16(sp)
ld s2, 24(sp)
addi sp, sp, 32
ret
# Open fd
# @param[in] a0: ptr to null-terminated file str.
# @param[out] a0: result code. (0-exists 1-doesn't exist)
# @param[out] a1: fd.
open_fd:
mv a1, a0 # since the function takes in a0, move it to a1 for syscall
li a0, -100 # relative/absolute path
li a2, 0 # readonly
li a7, 56 # open
ecall
bltz a0, 1f # file doesn't exist
mv a1, a0 # move fd to a1
li a0, 0
j 2f
1:
li a0, 1
2:
ret
-215
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@@ -1,215 +0,0 @@
.data
cat_buf: .space 4096
endings_buf: .space 4097
.section .text
.globl cat_file, open_fd, cat_stdin
# Cat out the given file to stdout
# @param[in] a0: ptr to null-terminated file str.
# @param[out] a0: result code.
cat_file:
addi sp, sp, -24
sd s0, 0(sp)
sd ra, 8(sp)
sd s1, 16(sp)
mv a1, a0 # since the function takes in a0, move it to a1 for syscall
addi sp, sp, -8
sd ra, 0(sp)
call open_fd
ld ra, 0(sp)
addi sp, sp, 8
mv s0, a1 # put fd in s0
la t1, show_ends
lb s1, 0(t1) # store if we show ends into s1
beqz a0, .LReadFileBlock # if we don't have an error, jump to reading
li a0, 1
j .LCatFileRet
.LReadFileBlock:
mv a0, s0
la a1, cat_buf
li a2, 4096
li a7, 63
ecall
blez a0, .LCloseFD # if we haven't read any bytes, EOF, close FD
beqz s1, .LNoEndingsWrite
mv a1, a0
la a0, cat_buf
call _stdout_add_endings
j .LReadFileBlock
.LNoEndingsWrite:
mv a2, a0 # load the amount of bytes read in previous step into bytes needed to write
li a0, 1
la a1, cat_buf
li a7, 64
ecall
j .LReadFileBlock
.LCloseFD:
mv a0, s0
li a7, 57 # close fd
ecall
.LCatFileRet:
ld s0, 0(sp)
ld ra, 8(sp)
ld s1, 16(sp)
addi sp, sp, 24
ret
# Cat out stdin to stdout
# @param[in] a0: Not used.
# @param[out] a0: Not used.
cat_stdin:
addi sp, sp, -16
sd ra, 0(sp)
sd s0, 8(sp)
la t1, show_ends
lb s0, 0(t1) # store if we show ends into s1
.LReadStdinBlock:
li a0, 0
la a1, cat_buf
li a2, 4096
li a7, 63
ecall
blez a0, .LCatStdinRet # if we haven't read any bytes, EOF, close FD
beqz s0, .LNoEndingsStdinWrite
mv a1, a0
la a0, cat_buf
call _stdout_add_endings
j .LReadStdinBlock
.LNoEndingsStdinWrite:
mv a2, a0 # move bytes read into bytes needed to write
li a0, 1
la a1, cat_buf
li a7, 64
ecall
j .LReadStdinBlock
.LCatStdinRet:
ld ra, 0(sp)
ld s0, 8(sp)
addi sp, sp, 16
ret
# Open fd
# @param[in] a0: ptr to null-terminated file str.
# @param[out] a0: result code. (0-exists 1-doesn't exist)
# @param[out] a1: fd.
open_fd:
mv a1, a0 # since the function takes in a0, move it to a1 for syscall
li a0, -100 # relative/absolute path
li a2, 0 # readonly
li a7, 56 # open
ecall
bltz a0, 1f # file doesn't exist
mv a1, a0 # move fd to a1
li a0, 0
j 2f
1:
li a0, 1
2:
ret
# Print to stdout while adding "$" characters.
# @param[in] a0: ptr to null-terminated str.
# @param[in] a1: length of str.
# @param[out] a0: result code.
_stdout_add_endings:
addi sp, sp, -72
sd s7, 64(sp)
sd s6, 56(sp)
sd s5, 48(sp)
sd s4, 40(sp)
sd ra, 32(sp)
sd s3, 24(sp)
sd s2, 16(sp)
sd s1, 8(sp)
sd s0, 0(sp)
mv s0, a0 # put the cat_buf ptr in s0
mv s1, a1
li s2, 0 # set the cat_buf char counter to 0
li s3, 0 # set the endings_buf char counter to 0
la s5, endings_buf
.LStdoutEndingsProcessChunk:
add s4, s0, s2 # Calculate the offset address
lb t6, 0(s4)
li t4, 0xA # newline
bne t6, t4, 1f # if the current byte is not a newline, skip to writing
add s4, s5, s3 # s4 = endings_buf[s2]
li t5, '$'
sb t5, 0(s4) # endings_buf[s2] = $
li t5, '\n'
addi s4, s4, 1
sb t5, 0(s4) # endings_buf[s2] = \n
addi s3, s3, 2
li a0, 1
la a1, endings_buf
mv a2, s3
li a7, 64
ecall
call _zero_endings_buf
li s3, 0 # reset endings_buf char counter
j 2f
1:
add s4, s5, s3 # s4 = endings_buf[s2]
sb t6, 0(s4) # endings_buf[s2] = t6
addi s3, s3, 1 # inc endings_buf pointer
2:
addi s2, s2, 1 # inc cat_buf pointer
blt s2, s1, .LStdoutEndingsProcessChunk
beqz s3, .LSkipEndingsPrint
li a0, 1
la a1, endings_buf
mv a2, s3
li a7, 64
ecall
.LSkipEndingsPrint:
li a0, 0
ld s0, 0(sp)
ld s1, 8(sp)
ld s2, 16(sp)
ld s3, 24(sp)
ld ra, 32(sp)
ld s4, 40(sp)
ld s5, 48(sp)
ld s6, 56(sp)
ld s7, 64(sp)
addi sp, sp, 72
ret
_zero_endings_buf:
li t0, 0
li t1, 4097
.LZeroEndingsBufByte:
la t2, endings_buf
add t2, t2, t0
sb x0, 0(t2)
addi t0, t0, 1
blt t0, t1, .LZeroEndingsBufByte
ret
+47 -4
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@@ -1,6 +1,8 @@
.data
argc: .space 8
show_ends: .space 1
number: .space 1
number_nonblank: .space 1
cat_prefix: .ascii "cat: "
.equ CAT_PREFIX_LEN, . - cat_prefix
@@ -12,14 +14,16 @@ help:
.ascii "Usage: cat [OPTION]... [FILE]...\n"
.ascii "Concatenate FILE(S) to standard output.\n\n"
.ascii "With no FILE, or when FILE is -, read standard input.\n\n"
.ascii " -b, --number-nonblank number nonempty output lines, overrides -n\n"
.ascii " -E, --show-ends display $ at end of each line\n"
.ascii " -n, --number number all output lines\n"
.ascii " --help display this help and exit\n"
.ascii " --version output version information and exit\n\n"
.asciz "Git repository: <https://git.lexza.ch/Lexzach/riscv-cat>\n"
.equ HELP_LEN, . - help
version:
.ascii "cat 1.1.0\n"
.ascii "cat 1.4.0\n"
.ascii "Copyright (C) 2026 lexzach\n"
.ascii "License MIT\n"
.ascii "This is free software: you are free to change and redistribute it.\n"
@@ -31,9 +35,13 @@ flag_help: .asciz "--help"
flag_version: .asciz "--version"
flag_show_ends: .asciz "--show-ends"
flag_E: .asciz "-E"
flag_number: .asciz "--number"
flag_n: .asciz "-n"
flag_number_nonblank: .asciz "--number-nonblank"
flag_b: .asciz "-b"
.section .text
.globl _start, show_ends
.globl _start, show_ends, number, number_nonblank
# main.
_start:
@@ -48,6 +56,8 @@ _start:
li s1, 1
li s2, 0 # processed files
call zero_line_count
bnez a0, .LMainReturnErr
call _check_flags
li t0, 1
@@ -61,9 +71,9 @@ _start:
addi sp, sp, -8
sd a0, 0(sp)
call _is_known_flag
bnez a1, .LSkipArg # check if arg is flag
ld a0, 0(sp)
addi sp, sp, 8
bnez a1, .LSkipArg # check if arg is flag
call cat_file
addi s2, s2, 1
bnez a0, .LReturnFileErr # error if failed
@@ -74,7 +84,8 @@ _start:
j .LMainReturnOk
.LProcessStdin:
call cat_stdin
li a0, 0
call cat_file
j .LMainReturnOk
.LReturnFileErr:
@@ -149,6 +160,18 @@ _check_flags:
bnez a0, .LMainReturnErr
sb a1, show_ends, t1 # since the return for has switch is either 0 for not found or 1 for found, we can just write it directly into the buf
la a0, flag_number
la a1, flag_n
call has_switch
bnez a0, .LMainReturnErr
sb a1, number, t1
la a0, flag_number_nonblank
la a1, flag_b
call has_switch
bnez a0, .LMainReturnErr
sb a1, number_nonblank, t1
ld ra, 0(sp)
addi sp, sp, 8
ret
@@ -184,6 +207,26 @@ _is_known_flag:
call str_cmp
bnez a1, .LFlagFound
la a0, flag_number
mv a1, s0
call str_cmp
bnez a1, .LFlagFound
la a0, flag_n
mv a1, s0
call str_cmp
bnez a1, .LFlagFound
la a0, flag_number_nonblank
mv a1, s0
call str_cmp
bnez a1, .LFlagFound
la a0, flag_b
mv a1, s0
call str_cmp
bnez a1, .LFlagFound
li a1, 0
.LFlagFound:
ld s0, 0(sp)
+235
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@@ -0,0 +1,235 @@
.data
line_count: .space 6
.section .text
.globl add_endings, add_line_numbers, zero_line_count
# Print to stdout while adding "$" characters.
# @param[in] a0: ptr to null-terminated str.
# @param[in] a1: length of str.
# @param[in] a2: mod buf addr.
# @param[out] a0: result code.
# @param[out] a1: bytes written to mod buf.
add_endings:
addi sp, sp, -56
sd s5, 48(sp)
sd s4, 40(sp)
sd ra, 32(sp)
sd s3, 24(sp)
sd s2, 16(sp)
sd s1, 8(sp)
sd s0, 0(sp)
mv s0, a0 # put the str buf ptr in s0
mv s1, a1
li s2, 0 # set the str buf char counter to 0
li s3, 0 # set the mod buf char counter to 0
mv s5, a2
.LEndingsProcessChunk:
add s4, s0, s2 # Calculate the offset address
lb t6, 0(s4)
li t4, 0xA # newline
bne t6, t4, 1f # if the current byte is not a newline, skip to writing
add s4, s5, s3 # s4 = mod buf[s2]
li t5, '$'
sb t5, 0(s4) # mod buf[s2] = $
li t5, '\n'
addi s4, s4, 1
sb t5, 0(s4) # mod buf[s2] = \n
addi s3, s3, 2
j 2f
1:
add s4, s5, s3 # s4 = mod buf[s2]
sb t6, 0(s4) # mod buf[s2] = t6
addi s3, s3, 1 # inc mod buf pointer
2:
addi s2, s2, 1 # inc str buf pointer
blt s2, s1, .LEndingsProcessChunk
li a0, 0
mv a1, s3
ld s0, 0(sp)
ld s1, 8(sp)
ld s2, 16(sp)
ld s3, 24(sp)
ld ra, 32(sp)
ld s4, 40(sp)
ld s5, 48(sp)
addi sp, sp, 56
ret
# Prefix newlines with ######+TAB line count
# @param[in] a0: ptr to null-terminated str.
# @param[in] a1: length of str.
# @param[in] a2: mod buf addr.
# @param[out] a0: result code.
# @param[out] a1: bytes written to mod buf.
add_line_numbers:
addi sp, sp, -72
sd s7, 64(sp) # skip empty
sd s6, 56(sp) # mod buf ptr
sd s5, 48(sp) # mod buf bp
sd s4, 40(sp) # str buf ptr
sd ra, 32(sp)
sd s3, 24(sp) # mod buf offset
sd s2, 16(sp) # str buf offset
sd s1, 8(sp) # len of str
sd s0, 0(sp) # str buf addr
la t0, number_nonblank
lb s7, 0(t0)
mv s0, a0 # put the str ptr in s0
mv s1, a1 # move length of str into s1
li s2, 0 # set the str buf char offset to 0
li s3, 0 # set the mod buf char offset to 0
mv s5, a2 # move mod buf addr into s5
# there is always one line number at the very start
call _inc_line_count
li t2, 0 # lc char buf offset
li t3, 6 # lc char buf max offset
la t1, line_count # load the line count buffer addr
add s6, s5, s3 # update mod buf + offset addr
4:
add t4, t1, t2
lb t5, 0(t4)
sb t5, 0(s6) # mod buf[s4] = t4
addi t2, t2, 1
addi s3, s3, 1
add s6, s5, s3 # update mod buf + offset addr
blt t2, t3, 4b
li t5, 0x9 # tab character
sb t5, 0(s6)
addi s3, s3, 1
.LLineNumbersProcessChunk:
add s4, s0, s2 # Calculate the offset address
lb t6, 0(s4)
li t4, 0xA # newline
bne t6, t4, 1f # if the current byte IS NOT a newline, skip to writing
mv t0, s2
addi t0, t0, 1 # move ahead one char and see if EOF
bge t0, s1, 1f # if the newline is at the very end, we don't indicate a new line number
beqz s7, .LLineNumbersSkipEmptyCheck
mv t0, s4 # move the current string buf pointer into t0
addi t0, t0, 1 # move the str pointer forward one
lb t0, 0(t0)
# t4 still contains a newline char
beq t0, t4, 1f # if the next byte IS a newline, skip to writing
.LLineNumbersSkipEmptyCheck:
call _inc_line_count
addi s3, s3, 1 # we want the ptr at the spot right after the newline
add s6, s5, s3 # update mod buf + offset addr
li t2, 0 # lc char buf offset
li t3, 6 # lc char buf max offset
la t1, line_count # load the line count buffer addr
li t5, 0xA # newline character
sb t5, 0(s6)
addi s3, s3, 1
add s6, s5, s3 # update mod buf + offset addr
3:
add t4, t1, t2
lb t5, 0(t4)
sb t5, 0(s6) # mod buf[s4] = t4
addi t2, t2, 1
addi s3, s3, 1
add s6, s5, s3 # update mod buf + offset addr
blt t2, t3, 3b
li t5, 0x9 # tab character
sb t5, 0(s6)
addi s3, s3, 1
j 2f
1:
add s6, s5, s3 # s4 = mod buf[s2]
sb t6, 0(s6) # mod buf[s2] = t6
addi s3, s3, 1 # inc mod buf pointer
2:
addi s2, s2, 1 # inc str buf pointer
blt s2, s1, .LLineNumbersProcessChunk
li a0, 0
mv a1, s3
ld s0, 0(sp)
ld s1, 8(sp)
ld s2, 16(sp)
ld s3, 24(sp)
ld ra, 32(sp)
ld s4, 40(sp)
ld s5, 48(sp)
ld s6, 56(sp)
ld s6, 64(sp)
addi sp, sp, 72
ret
# Increment the line count string
# @param[in] a0: not used
# @param[out] a0: result code
_inc_line_count:
la t0, line_count # load the line count buffer address
li t1, 5 # current offset, we move from right to left first
.LIncLine:
bltz t1, .LLineCountDoneInc
add t2, t0, t1 # load the correct offset address into t2
lb t3, 0(t2) # load the current ascii character into t3
li t4, 32 # load space character
bne t3, t4, .LLineCountNotSpaceChar # if the character is not a space, skip setting to zero
li t4, 48 # ascii '0'
sb t4, 0(t2) # store this at the current pointer
.LLineCountNotSpaceChar:
add t2, t0, t1 # load the correct offset address into t2
lb t3, 0(t2) # load the current ascii character into t3
li t4, 58 # ascii ':', right after ascii '9', overflow
addi t3, t3, 1
beq t3, t4, .LLineCountOverflow
sb t3, 0(t2)
j .LLineCountDoneInc
.LLineCountOverflow:
li t4, 48 # ascii '0'
sb t4, 0(t2) # store that ascii '0'
li t4, 1
sub t1, t1, t4 # move to the next digit to the left
j .LIncLine
.LLineCountDoneInc:
ret
# Set the line count to all space characters
# @param[in] a0: not used
# @param[out] a0: result code
zero_line_count:
la t0, line_count # load the line count buffer address
li t1, 0 # char ptr
li t2, 6 # max char
li t3, 32 # space character
1:
add t4, t0, t1 # load offset addr
sb t3, 0(t4) # store the space char in offset addr
addi t1, t1, 1
blt t1, t2, 1b
li a0, 0
ret