This chapter examines some more advanced concepts related to process management, which are found in a number of contemporary operating systems. We show that the concept of process is more complex and subtle than presented so far and in fact embodies two separate and potentially independent concepts: one relating to resource ownership and another relating to execution. | CSC 221 Computer Organization and Assembly Language Lecture 25: Advanced Procedures in Assembly Lecture 24: Review LOCAL flagVals[20]:BYTE ; array of bytes LOCAL pArray:PTR WORD ; pointer to an array myProc PROC, ; procedure LOCAL t1:BYTE, ; local variables LOCAL Directive Examples: MASM-Generated Code (1 of 2) BubbleSort PROC LOCAL temp:DWORD, SwapFlag:BYTE . . . ret BubbleSort ENDP BubbleSort PROC push ebp mov ebp,esp add esp,0FFFFFFF8h ; add -8 to ESP . . . mov esp,ebp pop ebp ret BubbleSort ENDP MASM generates the following code: MASM-Generated Code (2 of 2) Diagram of the stack frame for the BubbleSort procedure: INVOKE Directive The INVOKE directive is a powerful replacement for Intel’s CALL instruction that lets you pass multiple arguments. Syntax: INVOKE procedureName [, argumentList] argumentList is an optional comma-delimited list of procedure arguments. Arguments can be: immediate values and integer expressions variable names address and ADDR expressions register names ADDR Operator .data myWord WORD ? .code INVOKE mySub,ADDR myWord Returns a near or far pointer to a variable, depending on which memory model your program uses: Small model: returns 16-bit offset Large model: returns 32-bit segment/offset Flat model: returns 32-bit offset Simple example: PROC Directive The PROC directive declares a procedure with an optional list of named parameters. Syntax: label PROC paramList paramList is a list of parameters separated by commas. Each parameter has the following syntax: paramName : type type must either be one of the standard ASM types (BYTE, SBYTE, WORD, etc.), or it can be a pointer to one of these types. AddTwo Procedure (1 of 2) AddTwo PROC, val1:DWORD, val2:DWORD mov eax,val1 add eax,val2 ret AddTwo ENDP The AddTwo procedure receives two integers and returns their sum in EAX. PROC Examples (2 of 3) FillArray PROC, pArray:PTR BYTE, fillVal:BYTE arraySize:DWORD mov ecx,arraySize mov esi,pArray mov al,fillVal L1: mov [esi],al inc esi loop L1 ret . | CSC 221 Computer Organization and Assembly Language Lecture 25: Advanced Procedures in Assembly Lecture 24: Review LOCAL flagVals[20]:BYTE ; array of bytes LOCAL pArray:PTR WORD ; pointer to an array myProc PROC, ; procedure LOCAL t1:BYTE, ; local variables LOCAL Directive Examples: MASM-Generated Code (1 of 2) BubbleSort PROC LOCAL temp:DWORD, SwapFlag:BYTE . . . ret BubbleSort ENDP BubbleSort PROC push ebp mov ebp,esp add esp,0FFFFFFF8h ; add -8 to ESP . . . mov esp,ebp pop ebp ret BubbleSort ENDP MASM generates the following code: MASM-Generated Code (2 of 2) Diagram of the stack frame for the BubbleSort procedure: INVOKE Directive The INVOKE directive is a powerful replacement for Intel’s CALL instruction that lets you pass multiple arguments. Syntax: INVOKE procedureName [, argumentList] argumentList is an optional comma-delimited list of procedure arguments. Arguments can be: immediate values and integer expressions variable names address and ADDR expressions register names .
