src/args.S

@@ -107,9 +107,9 @@ has_switch:
     mv s1, a1
 
     call fetch_argc
-    bnez a0, 1f
+    bnez a0, .LHasSwitchNoParse
     li t0, 2
-    blt a1, t0, 1f # if we have no commands other than the binary, we know there will be no switches
+    blt a1, t0, .LSwitchNotFoundNoParse # if we have no commands other than the binary, we know there will be no switches
 
     addi sp, sp, -24
     sd s4, 16(sp)
@@ -118,7 +118,7 @@ has_switch:
     li s2, 1 # load first non-base command arg
     mv s4, a1 # put argc in s4
     
-    2:
+    .LSwitchProcessNextArg:
     mv a0, s2
     call fetch_argv
     mv s3, a1 # save argv buff addr
@@ -126,32 +126,37 @@ has_switch:
     mv a0, s3 # load argv buff addr into a0 (string 0)
     mv a1, s0 # move switch ptr 1 addr into a1 (string 1)
     call _str_cmp
-    bnez a1, 5f # if the strings match, exit loop
+    bnez a1, .LSwitchFound # if the strings match, exit loop
 
     mv a0, s3 # move argv buff addr into a0 (string 0)
     mv a1, s1 # move switch ptr 2 addr into a1 (string 1)
     call _str_cmp
-    bnez a1, 5f # if the strings match, exit loop
+    bnez a1, .LSwitchFound # if the strings match, exit loop
 
     addi s2, s2, 1 # if string doesn't match we inc to the next arg
-    blt s2, s4, 2b # keep going while we have untested args
+    blt s2, s4, .LSwitchProcessNextArg # keep going while we have untested args
     
-    4:
+    .LSwitchNotFound:
     li a0, 0
     li a1, 0
-    j 3f
+    j .LSwitchFreeSP
 
-    5:
+    .LSwitchNotFoundNoParse:
+    li a0, 0
+    li a1, 0
+    j .LHasSwitchNoParse
+
+    .LSwitchFound:
     li a0, 0
     li a1, 1
 
-    3:
+    .LSwitchFreeSP:
     ld s3, 0(sp)
     ld s2, 8(sp)
     ld s4, 16(sp)
     addi sp, sp, 24
 
-    1:
+    .LHasSwitchNoParse:
     ld ra, 16(sp)
     ld s1, 8(sp)
     ld s0, 0(sp)

src/file.S

@@ -2,7 +2,7 @@
 cat_buf:    .space 4096
 
 .section .text
-.globl cat_file, open_fd
+.globl cat_file, open_fd, cat_stdin
 
 # Cat out the given file to stdout
 # @param[in] a0: ptr to null-terminated file str.
@@ -17,12 +17,12 @@ cat_file:
     addi sp, sp, 8
 
     mv t0, a1 # put fd in t0
-    beqz a0, .LReadBlock # if we don't have an error, jump to reading
+    beqz a0, .LReadFileBlock # if we don't have an error, jump to reading
     li a0, 1
-    j .LRet
+    j .LCatFileRet
 
 
-    .LReadBlock:
+    .LReadFileBlock:
     mv a0, t0
     la a1, cat_buf
     li a2, 4096
@@ -35,16 +35,37 @@ cat_file:
     la a1, cat_buf
     li a7, 64
     ecall
-    j .LReadBlock
+    j .LReadFileBlock
     
     .LCloseFD:
     mv a0, t0
     li a7, 57 # close fd
     ecall
 
-    .LRet:
+    .LCatFileRet:
     ret
 
+# Cat out stdin to stdout
+# @param[in] a0: Not used.
+# @param[out] a0: result code.
+cat_stdin:
+    .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
+    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:
+    ret
 
 # Open fd
 # @param[in] a0: ptr to null-terminated file str.

src/main.S

@@ -10,6 +10,7 @@ file_err:       .asciz ": No such file or directory\n"
 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 "    -h, --help  |  Show this help page.\n\n"
     .asciz "Written by lexzach in RISC-V assembly: <https://git.lexza.ch/Lexzach/riscv-cat>\n"
 .equ HELP_LEN, . - help
@@ -29,45 +30,37 @@ _start:
 
     call save_sp
     call fetch_argc
-    li t0, 1
-    ble a1, t0, .Lreturn_err # return 1 if no args
     mv s0, a1 # store argc
     li s1, 1
 
     la a0, flag_h
     la a1, flag_help
     call has_switch
-    bnez a0, .Lreturn_err
+    bnez a0, .LMainReturnErr
-    beqz a1, .Lskip_disp_help
+    beqz a1, .LSkipDispHelp
     call _disp_help
-    j .Lreturn_ok
+    j .LMainReturnOk
-    .Lskip_disp_help:
+    .LSkipDispHelp:
     
-
+    li t0, 1
-    # 5: #iterate through and check that all files exist first
+    ble s0, t0, .LProcessStdin # return 1 if no args
-    # mv a0, s1
+    
-    # call fetch_argv
+    .LProcessFile:
-    # bnez a0, 1f # error if failed
-    # mv a0, a1
-    # call file_exists
-    # bnez a0, 4f
-    # addi s1, s1, 1
-    # blt s1, s0, 5b
-
-    # li s1, 1 # reset counter now that we've verified all files exist, skip command
-
-    .Lprocess_file:
     mv a0, s1
     call fetch_argv
-    bnez a0, .Lreturn_err # error if failed
+    bnez a0, .LMainReturnErr # error if failed
     mv a0, a1
     call cat_file
-    bnez a0, .Lreturn_file_err # error if failed
+    bnez a0, .LReturnFileErr # error if failed
     addi s1, s1, 1
-    blt s1, s0, .Lprocess_file
+    blt s1, s0, .LProcessFile
-    j .Lreturn_ok
+    j .LMainReturnOk
-
+    
-    .Lreturn_file_err:
+    .LProcessStdin:
+    call cat_stdin
+    j .LMainReturnOk
+    
+    .LReturnFileErr:
     li a0, 2
     la a1, cat_prefix
     li a2, CAT_PREFIX_LEN
@@ -88,12 +81,12 @@ _start:
     ecall
     
 
-    .Lreturn_err: #1
+    .LMainReturnErr: #1
     li a0, 1
     li a7, 93
     ecall # return 1
 
-    .Lreturn_ok: #2
+    .LMainReturnOk: #2
     li a0, 0
     li a7, 93
     ecall   # return 0