Work on inc line count function

src/main.S

@@ -52,6 +52,8 @@ _start:
     li s1, 1
     li s2, 0 # processed files
     
+    call zero_line_count
+    bnez a0, .LMainReturnErr
     call _check_flags
 
     li t0, 1

src/mod.S

@@ -1,8 +1,8 @@
 .data
-line_count:     .space 8
+line_count:     .space 6
 
 .section .text
-.globl add_endings, add_line_numbers
+.globl add_endings, add_line_numbers, zero_line_count
 
 # Print to stdout while adding "$" characters.
 # @param[in] a0: ptr to null-terminated str.
@@ -132,3 +132,57 @@ add_line_numbers:
     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, 5 # 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