120 lines
3.4 KiB
ArmAsm
120 lines
3.4 KiB
ArmAsm
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;/******************************************************************************
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; * file: for_asm_calls.S
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; * function: save and restore scratch registers
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; * ----------------------------------------------------------------------------
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; * comments: These calls are used in the first assembler laboratories
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; * to hide the scratch register usage
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; *****************************************************************************/
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EXPORT decOut
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EXPORT strOut
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EXPORT decIn
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EXPORT strIn
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IMPORT printf
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IMPORT scanf
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IMPORT getchar
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AREA |.text|, CODE, READONLY
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;/******************************************************************************
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; * name: decOut
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; * function: display a decimal value on the debug terminal
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; * ----------------------------------------------------------------------------
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; * parameters: r0 - the value to display
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; *
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; * comments: use USE_STDIO_NOBUF 1 in config.h to print direclty the value
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; * on the serial port
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; *****************************************************************************/
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decOut
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push {r0-r3,ip,lr}
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mov r1,r0
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ldr r0,=strDecOut
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bl printf
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pop {r0-r3,ip,pc}
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;/******************************************************************************
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; * name: strOut
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; * function: display a string on the debug terminal
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; * The string has to finish with a NULL character
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; * ----------------------------------------------------------------------------
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; * parameters: r0 - the string pointer
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; *
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; * comments: use USE_STDIO_NOBUF 1 in config.h to print direclty the value
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; * on the serial port
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; *****************************************************************************/
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strOut
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push {r0-r3,ip,lr}
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mov r1,r0
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ldr r0,=strStrOut
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bl printf
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pop {r0-r3,ip,pc}
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;/******************************************************************************
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; * name: decIn
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; * function: read a decimal value on the debug terminal
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; * The value ends with a CR (as standard scanf)
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; * ----------------------------------------------------------------------------
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; * parameters: -
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; *
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; * return: r0 - the readed value
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; *
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; * comments: use USE_STDIO_ECHO 1 in config.h to have an echo
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; * on the serial port when typing
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; *****************************************************************************/
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decIn
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push {r1-r4,ip,lr}
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ldr r0,=strDecIn
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ldr r1,=readVal
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bl scanf
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bl getchar ; flush CR
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ldr r1,=readVal
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ldr r0,[r1]
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pop {r1-r4,ip,pc}
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;/******************************************************************************
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; * name: strIn
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; * function: reads a string on the debug terminal
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; * The string ends with a CR
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; * ----------------------------------------------------------------------------
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; * parameters: r0 - the string pointer
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; * r1 - length max
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; *
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; * comments: use USE_STDIO_ECHO 1 in config.h to have an echo
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; * on the serial port when typing
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; *****************************************************************************/
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strIn
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push {r0-r5,ip,lr}
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mov r4,r1
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mov r5,r0
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loopStrIn
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mov r1,r5
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bl getchar
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cmp r0,#0x0D
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beq replaceCrStrIn
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strb r0,[r5]
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sub r4,r4,#1
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cmp r4,#0
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beq endNull
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add r5,r5,#1
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b loopStrIn
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replaceCrStrIn
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mov r0,#0
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strb r0,[r5]
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pop {r0-r5,ip,pc}
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endNull
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mov r1,#0
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strb r1,[r5,#1]
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pop {r0-r5,ip,pc}
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;/* strings for printf and scanf usage */
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strDecOut DCB "%ld",0
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strDecIn DCB "%ld",0
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strStrOut DCB "%s",0,0
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AREA |.data|, DATA, READWRITE, ALIGN=4
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readVal DCD 0 ;/* one word byte for read */
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END
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