Could some1 explain me the algorithm of whats happening int he keypad.bas?

I ve been trying to figure out and it doesnt make a whole lot of sense to me

So my Kb_row_bit =0 and kb_col_bit=4 (initially)
how does the algorithm take care of the scanning from here?
I think I understood a few iterations but I am not toosure I
totally understand

Below are teh subroutines from that file that I think are managing the scanning process

Scan the Keypad
' ===============
repeat
key=0 ' no key is press
row=0 ' begin scan @ ROW0
col=0 ' COL0
kb_row_PORT=kb_row_PORT | InitialState ' set all ROW bits to 1
repeat
ROWBIT=ROW+KB_ROW_BIT ' point to a ROW bit
kb_row_PORT.0[RowBit]=0 ' clear actual ROW bit

Gosub readcol ' Read column
if KeyTemp != KeyMask then ' Any column to 0?
REPEAT ' YES
IF KeyTemp.0=0 THEN ' IF the actual column=0
key=row*KB_COL ' Calculate
key=key+col ' the
key=key+1 ' Value
row=KB_ROW ' Set maximum ROW to getout of here
@ ifndef KEYPAD_AUTOREPEAT ' If AutoRepeat is not DEFINE
repeat
Gosub readcol ' Wait until
until KeyTemp=keymask ' Key is released
@ endif
PAUSE DebounceDelay ' Debounce delay
ENDIF
keytemp=keytemp>>1 ' shift to next column bit
Col=col+1 ' go to next column
UNTIL COL=KB_COL ' COL scan Finished?
endif

kb_row_PORT.0[Rowbit]=1 ' set actual ROW bit
row=row+1 ' point to next row
until row>(KB_ROW-1)
until key!=0 ' Row scan finished?
RETURN ' any key pressed?

ReadCol:
KeyTemp=kb_col_PORT>>kb_col_Bit ' Read Column state
KeyTemp=KeyTemp & kEYMASK ' Keep only wanted bits
return