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108 lines
3.0 KiB
108 lines
3.0 KiB
page ,132
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subttl emstack.asm - Emulator Stack Management Area
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;***
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;emstack.asm - Emulator Stack Management Area
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;
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; Copyright (c) 1986-89, Microsoft Corporation
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;
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;Purpose:
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; Emulator Stack Management Area
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;
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; This Module contains Proprietary Information of Microsoft
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; Corporation and should be treated as Confidential.
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;
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;Revision History:
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; See emulator.hst
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;
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;*******************************************************************************
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ProfBegin STACK
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;*********************************************************************;
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; ;
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; Emulator Stack Management Area ;
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; ;
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;*********************************************************************;
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; The emulator maintains an "finite" stack of 12 byte registers.
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; Stand-alone emulator has 1 chunk only.
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; This is done using a list of finite length stack chunks, each of
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; which has the following format:
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; +00 first (deepest) 12 byte register
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; +12 next 12 byte register
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; (and so on through last possible register)
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; MACROS used to manipulate the emulator/8087 memory stack
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; This macro allocates a new TOS register, returns SI with its address.
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PUSHST MACRO
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local pushstok
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mov esi,[CURstk] ; 14 get address of current register
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cmp esi,[LIMstk] ; 15 is current register end of stack
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jne short pushstok ; 16 no, still room in stack
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call OverStk ; stack overflow error
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pushstok:
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add esi,Reg87Len ; 4 increment SI to next free register
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mov [CURstk],esi ; 15 set current top of stack
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ENDM ; 64 total
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; This macro deallocates TOS register, returns SI with new TOS address.
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; Note: assumes SI contains TOS address, CURstk
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; BASstk converted back to a variable to enable macro use for 8087 stack
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; handling. Brad Verheiden, 4-13-84.
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POPSTsi MACRO
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local popstok
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cmp esi,[BASstk] ; 15 was it last register in the chunk ?
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jnz short popstok ; 16 no, still room in current chunk
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call UnderStk ; stack underflow error
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popstok:
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sub esi,Reg87Len ; 4 decrement SI to previous register
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mov [CURstk],esi ; 15 set current top of stack
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ENDM ; 64 total
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POPST MACRO
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mov esi,[CURstk]
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POPSTsi
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ENDM
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ChangeDIfromTOStoNOS MACRO
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sub edi,Reg87Len
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ENDM
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page
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; This area contains two procedures, OverStk and UnderStk,
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; which generate a stack overflow error.
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; OverStk: invoked within PUSHST macro
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; on entry, the stack is full
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; on return, SI contains address of base of stack
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; UnderStk: invoked within POPST macro
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; on entry, the stack is empty
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; on return, SI contains address of base of stack
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pub OverStk
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OR byte ptr [CURerr+1],StackOverflow/256 ; raise stack overflow
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CMP [Have8087],0 ; Is 8087 present
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JZ short OverStkEnd ; No - don't touch AX
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OR AH,StackOverflow/256 ; Indicate memory overflow for 8087
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pub OverStkEnd
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RET ; finished
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pub UnderStk
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OR byte ptr [CURerr+1],StackUnderflow/256 ; raise stack underflow
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RET ; finished
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ProfEnd STACK
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