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⌂ ∞ Lander on the Acorn Archimedes

Score bar: PrintHexNumber

       Name: PrintHexNumber                                          [Show more]
       Type: Subroutine
   Category: Score bar
    Summary: An unused routine that prints an 8-digit hexadecimal number on the
             second character row of the screen
  Deep dive: Unused code in Lander

    Context: See this subroutine in context in the source code
 References: No direct references to this subroutine in this source file




 Arguments:

   R1                               The number to print



.PrintHexNumber

 MOV     R0, #30                    \ Print a VDU 30 command to move the text
 SWI     OS_WriteC                  \ cursor to the top-left corner of the
                                    \ screen

 MOV     R0, #&0A                   \ Print a line feed (ASCII &0A) to move the
 SWI     OS_WriteC                  \ cursor down one line, to the start of the
                                    \ second line, which is where we print the
                                    \ score bar

 STMFD   R13!, {R0-R12, R14}        \ Store the registers that we want to use on
                                    \ the stack so they can be preserved

 MOV     R0, R1, LSR #28            \ Print the top nibble of the value in R1
 BL      PrintHexDigit

 MOV     R0, R1, LSR #24            \ Print the next nibble of the value in R1
 BL      PrintHexDigit

 MOV     R0, R1, LSR #20            \ Print the next nibble of the value in R1
 BL      PrintHexDigit

 MOV     R0, R1, LSR #16            \ Print the next nibble of the value in R1
 BL      PrintHexDigit

 MOV     R0, R1, LSR #12            \ Print the next nibble of the value in R1
 BL      PrintHexDigit

 MOV     R0, R1, LSR #8             \ Print the next nibble of the value in R1
 BL      PrintHexDigit

 MOV     R0, R1, LSR #4             \ Print the next nibble of the value in R1
 BL      PrintHexDigit

 MOV     R0, R1                     \ Print the bottom nibble of the value in R1
 BL      PrintHexDigit

 MOV     R0, #&A                    \ Print a line feed (ASCII &0A) and carriage
 SWI     OS_WriteC                  \ return (ASCII &0D) to move the cursor down
 MOV     R0, #&D                    \ to the start of the next line, ready to
 SWI     OS_WriteC                  \ print further numbers if required

 LDMFD   R13!, {R0-R12, PC}         \ Retrieve the registers that we stored on
                                    \ the stack and return from the subroutine