Source code of Windows XP (NT5)
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; Copyright (c) 1998 Microsoft Corporation
;
; @Doc DMusic16
;
; @Module DMHelp.asm - Helper functions |
;
; Thunk helpers for DMusic16.DLL
;
page ,132
TITLE $dos\usa\dmhelp.asm
.386
OPTION READONLY
OPTION OLDSTRUCTS
OPTION SEGMENT:USE16
.model LARGE,PASCAL
;?MEDIUM=1
;?QUIET=1
externDef TileBuffer:far16
externDef UntileBuffer:far16
externDef OutputDebugString:far16
;===========================================================================
;
; 64-bit integer struct as passed in from C routines
;
; This must match the definition in dmusic16.h
;
;
;===========================================================================
QUADWORD struc
qwLow dd ?
qwHigh dd ?
QUADWORD ends
.code dmhelp
;===========================================================================
EAXtoDXAX macro
shld edx, eax, 16 ; move HIWORD(eax) to dx
endm
DXAXtoEAX macro
ror eax, 16 ; xchg HIWORD(eax) and LOWORD(eax)
shrd eax, edx, 16 ; move LOWORD(edx) to HIWORD(eax)
endm
;===========================================================================
public dmTileBuffer
public dmUntileBuffer
public QuadwordDiv
externDef __FLATDS:abs
_DATA SEGMENT WORD USE16 PUBLIC 'DATA'
FlatData dw __FLATDS
ifdef DEBUG
szNotOwner db 'Critical section released by other than owner', 0
endif
_DATA ENDS
;===========================================================================
;
; @func DWORD | dmTileBuffer | Tile a 32-bit linear address as selectors
;
; @comm
;
; Take the 32-bit virtual address in <p dwFlatMemory> of length <p dwLength> and create
; tiled selectors for it. This is used to pass a region of memory to a 16 bit thunk
; as a huge pointer.
;
; @rdesc
;
; Returns a DWORD of tiling information, or 0 if the tiling could not be completed.
; The tiling information consists of a 16 bit selector in the high word and the
; number of tiled selectors in the low word. To make a 16:16 pointer to the
; block of memory, mask the low 16 bits of the tiling information to zero.
;
; @parm DWORD | dwFlatMemory | The linear address of the memory to tile
;
; @parm DWORD | dwLength | The length in bytes of the region to tile
;
align
dmTileBuffer proc far16 public,
dwFlatMemory:dword, dwLength:dword
push edi
push esi
mov eax, dwFlatMemory
mov ecx, dwLength
call TileBuffer
mov eax, ecx
EAXtoDXAX
pop esi
pop edi
ret
dmTileBuffer endp
;===========================================================================
;
; @func VOID | dmUntileBuffer | Untile a buffer
;
; @comm
;
; Free the tiled selectors allocated by dmTileBuffer. The buffer must have
; been previously tiles with <f dmTileBuffer>.
;
; @parm DWORD | dwTilingInfo | The tiling info returned by a previous call
; to <f dmTileBuffer>.
;
align
dmUntileBuffer proc far16 public,
dwTilingInfo:dword
push esi
push edi
mov ecx, dwTilingInfo
call UntileBuffer
pop edi
pop esi
ret
dmUntileBuffer endp
;===========================================================================
;
; @func VOID PASCAL | InitializeCriticalSection | Initialize a critical section
;
; @comm
;
; Initialize the critical section to not-in.
;
; @parm LPWORD | lpwCritSect | The critical section to initialize.
;
align
InitializeCriticalSection proc far16 public,
lpwCritSect:dword
push es
push di
les di, [lpwCritSect]
mov word ptr es:[di], 1
pop di
pop es
ret
InitializeCriticalSection endp
;===========================================================================
;
; @func WORD PASCAL | EnterCriticalSection | Enter a critical section
;
; @comm
;
; If fBlocking is set, then spin until we can get the critical section.
; Otherwise, return failure if we could not get it.
;
; @rdesc
; Returns
; 0 if we did not get the critical section
; A non-zero ID if we did get the critical section
;
; @parm LPWORD | lpwCritSect | A pointer to the critical section to enter
; @parm WORD | fBlocking | A flag to indicate that the function should block if the
; critical section is not immediately available
;
align
EnterCriticalSection proc far16 public,
lpwCritSect:dword,
fBlocking:word
push es
push di
les di, [lpwCritSect] ; -> critical section
mov cx, [fBlocking]
ecs_check:
dec word ptr es:[di] ; 1 -> 0 means we got it
; atomic on non-MP
jz short ecs_success
inc word ptr es:[di] ; Return to previous state
or cx, cx ; Blocking?
jnz short ecs_check ; Yes
xor ax, ax ; Non-blocking and failed
jmp ecs_done
ecs_success:
mov ax, 1
ecs_done:
pop di
pop es
ret
EnterCriticalSection endp
;===========================================================================
;
; @func VOID PASCAL | LeaveCriticalSection | Leave a critical section
;
; @comm
;
; Leave the critical section. wCritSectID must be the critical section ID returned
; by the matching call to <f EnterCriticalSection> (used to verify nesting in debug
; versions).
;
; @parm LPWORD | lpwCritSect | The critical section to leave
;
align
LeaveCriticalSection proc far16 public,
lpwCritSect:dword
push es
push di
les di, [lpwCritSect] ; -> critical section
inc word ptr es:[di] ; Reset to default value of 1
pop di
pop es
ret
LeaveCriticalSection endp
;===========================================================================
;
; @func WORD PASCAL | DisableInterrupts | Disable interrupts
;
; @comm
;
; Disable interrupts and return the previous status for a call to
; <f RestoreInterrupts>
;
; @rdesc
;
; Returns the previous state of the interrupt flag
;
;
DisableInterrupts proc far16 public
pushf
pop ax ; Get state
and ax, 0200h ; Already disabled?
jz short @F ; Don't do it again
cli
@@:
ret
DisableInterrupts endp
;===========================================================================
;
; @func VOID PASCAL | RestoreInterrupts | Restore the interrupt state
;
; @comm
;
; Restore interrupts if they were enabled when <f DisableInterrupts> was
; called.
;
; @parm WORD | wIntStat | The previous interrupt state as returned from a
; call to <f DisableInterrupts>
;
RestoreInterrupts proc far16 public,
wIntStat : word
mov ax, [wIntStat] ; Previous state
test ax, 0200h ; Enabled before?
jz short @F ; No, don't re-enable now
sti
@@:
ret
RestoreInterrupts endp
;===========================================================================
;
; @func WORD PASCAL | InterlockedIncrement | Increment the given word
; atomically and return the result.
;
; @comm
;
; Disable interrupts to guarantee increment-and-read as an atomic
; operation.
;
; @parm LPWORD | lpw | The word to increment.
;
InterlockedIncrement proc far16 public,
lpw : dword
pushf
pop cx
test cx, 0200h ; Were interrupts enabled?
jz @F ; No
cli ; Yes, disable
@@:
les bx, [lpw]
inc word ptr es:[bx]
mov ax, word ptr es:[bx]
test cx, 0200h ; Were interrupts enabled?
jz @F ; No
sti ; Yes, reenable
@@:
ret
InterlockedIncrement endp
;===========================================================================
;
; @func WORD PASCAL | InterlockedDecrement | Decrement the given word
; atomically and return the result.
;
; @comm
;
; Disable interrupts to guarantee decrement-and-read as an atomic
; operation.
;
; @parm LPWORD | lpw | The word to decrement.
;
InterlockedDecrement proc far16 public,
lpw : dword
pushf
pop cx
test cx, 0200h ; Were interrupts enabled?
jz @F ; No
cli ; Yes, disable
@@:
les bx, [lpw]
dec word ptr es:[bx]
mov ax, word ptr es:[bx]
test cx, 0200h ; Were interrupts enabled?
jz @F ; No
sti ; Yes, reenable
@@:
ret
InterlockedDecrement endp
;===========================================================================
;
; @func void PASCAL | QuadwordMul | Multiply using 64-bit precision
;
; @comm
;
; Multiply the two 32-bit numbers in <p m1> and <p m2> giving a 64-bit result
; in <p lpqwResult>.
;
; @rdesc
; Returns m1 * m2
;
; @parm DWORD | m1 | First multiplicand
; @parm DWORD | m2 | Second multiplicand
; @parm LPQUADWORD | lpqwResult | 64-bit result
;
QuadwordMul proc far16 public,
m1 : dword,
m2 : dword,
lpqwResult : dword
mov edx, [m1]
mov eax, [m2]
mul edx
les bx, [lpqwResult]
mov es:[bx.qwLow], eax
mov es:[bx.qwHigh], edx
ret
QuadwordMul endp
;===========================================================================
;
; @func DWORD PASCAL | QuadwordDiv | Divide using 64-bit precision
;
; @comm
;
; Divide the 64-bit number in <p ull> by the 32-bit number in <p dwDivisor> and
; return the result. May throw a divide by zero exception.
;
; @rdesc
; Returns ull / dwDivisor
;
; @parm QUADWORD | ull | The unsigned long dividend
; @parm DWORD | dwDivisor | The divisor
;
;
QuadwordDiv proc far16 public,
qwDividend : QUADWORD,
dwDivisor : dword
mov edx, [qwDividend.qwHigh]
mov eax, [qwDividend.qwLow]
mov ebx, [dwDivisor]
div ebx
; Result in eax, needs to be dx:ax for 16-bit code
ror eax, 16
mov dx, ax
ror eax, 16
ret
QuadwordDiv endp
;===========================================================================
;
; @func DWORD PASCAL | QuadwordLT | Compare two quadwords for less than (unsigned)
;
; @rdesc
; Returns TRUE if qwLValue < qwRValue
;
; @parm QUADWORD | qwLValue | The first operand of less-than
; @parm QUADWORD | qwRValue | The second operand of less-than
;
;
QuadwordLT proc far16 public,
qwLValue : QUADWORD,
qwRValue : QUADWORD
mov ebx, [qwLValue.qwHigh]
sub ebx, [qwRValue.qwHigh]
jz short @F
sbb eax, eax
ret
@@: mov ebx, [qwLValue.qwLow]
sub ebx, [qwRValue.qwLow]
sbb eax, eax
ret
QuadwordLT endp
;===========================================================================
;
; @func DWORD PASCAL | QuadwordAdd | Add two unsigned quadwords
;
; @parm QUADWORD | qwOp1 | The first operand
; @parm QUADWORD | qwOp2 | The second operand
; @parm LPQUADWORD | lpwqResult | The result
;
;
QuadwordAdd proc far16 public,
qwOp1 : QUADWORD,
qwOp2 : QUADWORD,
lpdwResult : DWORD
mov eax, [qwOp1.qwLow]
add eax, [qwOp2.qwLow]
mov edx, [qwOp1.qwHigh]
adc edx, [qwOp2.qwHigh]
les bx, [lpdwResult]
mov es:[bx.qwLow], eax
mov es:[bx.qwHigh], edx
ret
QuadwordAdd endp
end