// I have a problem using a far pointer to an array of word in memory. I
would appreciate
// any input one might have on where and what i'm doing wrong here.

// The array is currently set at 0xC0000

#define BASE  0xC0000
#define BASE_LSB BASE

The function prototype

extern "C" int ReadSensors  ( WORD _far *SAMPLES, WORD *BUFFER, WORD
NUMSMPL );

// This is called in an interrupt handler

LastSampleBuffer = (WORD _far*)BASE_LSB;
ReadSensors ( LastSampleBuffer, (WORD *)&LSWBuf, LCInit.NbC );

// LSWBuf is an array to a W,W,DW,W struct, this pointer does not seems to
be the problem since
// I use it in the other functions with success
// I have other functions in this asm module which transfer information
between
// buffers so it seems that my problem is comming from that far pointer
// I've tried using an array and it worked so it has to be about accessing
memory between 640K and 1M

s_WorkingBuffer LSWBuf[XNumOfSensors];

// Part of the ASM module

;  Called from main program in NEWLC.CPP
;  Assemble with ML /c BUFFERS.ASM

        .MODEL  large, c
        .386

ReadSensors   PROTO C SAMPLES:FAR PTR WORD, BUFFER:PTR WORD, NUMSMPL:WORD
UpdateWBuffer    PROTO C DSTBuf:PTR WORD, SRCBuf:PTR WORD, NUMSMPL:WORD
UpdateWBuffer10   PROTO C DSTBuf:PTR WORD, SRCBuf:PTR WORD, NUMSMPL:WORD

 .CODE

ReadSensors  PROC FAR  C SAMPLES:FAR PTR WORD, BUFFER:PTR WORD, NUMSMPL:WORD

  PUSHF

  MOV  CX, NUMSMPL
  JCXZ Done1

  PUSH ES
  PUSH DS
  PUSH SI
  PUSH DI

  PUSH EAX
  PUSH EBX

  LDS  SI, SAMPLES
  LES  DI, BUFFER

  CLD

 ReadLoop:
   LODSW            ; LastSample in AX

  MOV  BX, WORD PTR[DI]
  CMP  AX, BX             ; Compare to Buffer.Max
   JBE  NoHi                   ; Is it higher
   MOV  WORD PTR[DI], AX       ; Yes, update buffer
 NoHi:                         ; No, continue
  ADD  DI, 2

  MOV  BX, WORD PTR[DI]
   CMP  AX, BX            ; Compare to Buffer.Min
  JAE  NoLo                   ; Is it lower
   MOV  WORD PTR[DI], AX       ; Yes, update buffer
  NoLo:                         ; No, continue
  ADD  DI, 2
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;
    PUSH EAX
   CWDE

   MOV  EBX, DWORD PTR[DI]     ; Move Buffer.Total to BX
   ADD  EAX, EBX               ; Add sample to buffer
   MOV  DWORD PTR[DI], EAX     ; Update buffer

   POP  EAX                    ; Restore EAX
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;
  ADD  DI, 4

  MOV  BX, WORD PTR[DI]       ; Move Buffer.NumSample to BX
  INC  BX           ; Increment BX
   MOV  WORD PTR[DI], BX       ; Move back to buffer

  ADD  DI, 2

    LOOP ReadLoop               ; Next sample

  POP  EBX
  POP  EAX

  POP  DI
  POP  SI
  POP  DS
  POP  ES
 Done1:
  POPF
                RET
ReadSensors  ENDP

ADD     DI,2
MOV     AX,ES
MOV     BX,DI
SHR     BX,4
ADD     AX,BX
MOV     ES,AX
AND     DI,0FH

regards
Tony