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emm24_a.asm
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Assembly Source File
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1989-11-29
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16KB
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233 lines
;-----------------------------------------------------------------------------;
; MODULE NAME: EMM24_A.ASM ;
; ;
; FUNCTION NAME: move_memory_region ;
; ;
; DESCRIPTION: This function copies a region of memory in the ;
; following memory source/destination combinations. ;
; ;
; 1. conventional memory to conventional memory ;
; 2. conventional memory to expanded memory ;
; 3. expanded memory to conventional memory ;
; 4. expanded memory to expanded memory ;
; ;
; You do not have to save and restore the expanded memory ;
; mapping context to perform these move operations. The ;
; current mapping context is maintained throughout this ;
; operation. ;
; ;
; The length of the region is limited by the amount of ;
; expanded memory allocated to the handles specified. ;
; However, in most practical applications, the region ;
; length will be considerably smaller. A region length ;
; of zero is not an error, and no move will be performed. ;
; ;
; A region length which exceeds 16K bytes is not an ;
; error. In this case the function assumes that a group ;
; of logical pages is the target for the move. The ;
; logical page specified represents the first logical ;
; page in which the move will take place. If the region ;
; length exceeds 16K bytes, or if the region is less than ;
; 16K bytes but spans logical pages, there must be ;
; sufficient logical pages remaining after the first ;
; logical page for the entire region to fit. ;
; ;
; If your application needs to save a region of ;
; conventional memory in expanded memory, you can move it ;
; without having to perform a save or restore of the ;
; current mapping context. The memory manager maintains ;
; the context. A move of up to 1M byte may be performed, ;
; although practical lengths are substantially less than ;
; this value. ;
; ;
; If the source and destination handles are identical, ;
; the source and destination regions are tested for ;
; overlap before the move. If they overlap, the move ;
; direction is chosen so that the destination region ;
; receives an intact copy of the source region. A status ;
; will be returned indicating that this overlap has ;
; occurred. ;
; ;
; PASSED: &ms: ;
; is a far pointer to a structure which contains ;
; the source and destination information for the move. ;
; The structure members are described here: ;
; ;
; ms.region_size: ;
; is the length of the memory region (in bytes) to ;
; be moved. ;
; ;
; ms.source_mem_type: ;
; is the type of memory where the source region ;
; resides. A value of zero indicates that the ;
; source region resides in conventional memory ;
; (excluding the page frame segment). A value of ;
; one indicates that the source region resides in ;
; expanded memory. ;
; ;
; ms.source_handle: ;
; if the source region resides in expanded memory, ;
; it specifies the handle number associated with ;
; the source memory region. If the source region ;
; resides in conventional memory, it has no meaning ;
; and should be set to zero for future ;
; compatibility. ;
; ;
; ms.source_init_offset: ;
; is the offset within the source region at which ;
; to begin the move. ;
; ;
; If the source region resides in expanded memory, ;
; it specifies an offset relative to the beginning ;
; of the 16K-byte source page. Because the offset ;
; is relative to the beginning of a 16K-byte source ;
; expanded memory page, it may only take on values ;
; between 0000h and 3FFFh. ;
; ;
; If the source region resides in conventional ;
; memory, it specifies the offset, relative to the ;
; beginning of the source segment, at which to ;
; begin the move. Because the offset is relative ;
; to the beginning of a 64K-byte conventional ;
; memory segment, it may take on values between ;
; 0000h and FFFFh. ;
; ;
; ms.source_init_log_page_or_seg: ;
; is the initial segment or logical page number ;
; within the source region at which to begin the ;
; move. ;
; ;
; If the source region resides in expanded memory, ;
; it specifies the logical page within the source ;
; region at which to begin the move. ;
; ;
; If the source region resides in conventional ;
; memory, it specifies the initial segment address ;
; within conventional memory at which to begin ;
; the move. ;
; ;
; ms.dest_mem_type: ;
; is the type of memory where the destination ;
; region resides. A value of zero indicates ;
; conventional memory. A value of one indicates ;
; expanded memory. ;
; ;
; ms.dest_handle: ;
; if the destination region resides in expanded ;
; memory, it specifies the handle number associated ;
; with the destination memory region. ;
; ;
; If the destination region resides in conventional ;
; memory, it has no meaning and should be set to ;
; zero for future compatibility. ;
; ;
; ms.dest_init_offset: ;
; is the offset within the destination region at ;
; which to begin the move. ;
; ;
; If the destination region resides in expanded ;
; memory, it specifies an offset relative to the ;
; beginning of the 16K-byte destination page. ;
; Because the offset is relative to the beginning ;
; of a 16K-byte source expanded memory page, it may ;
; only take on values between 0000h and 3FFFh. ;
; ;
; If the destination region resides in conventional ;
; memory, it specifies the offset, relative to the ;
; beginning of the destination segment, to begin ;
; the move. Because the offset is relative to the ;
; beginning of a 64K conventional memory segment, ;
; it may take on values between 0000h and FFFFh. ;
; ;
; ms.dest_init_log_page_or_seg: ;
; is the initial segment or logical page number ;
; within the destination region at which to begin ;
; the move. ;
; ;
; If the destination region resides in expanded ;
; memory then the value specifies the logical page ;
; within the destination region at which to begin ;
; the move. ;
; ;
; If the destination region resides in conventional ;
; memory, it specifies the initial segment address ;
; within conventional memory at which to begin ;
; the move. ;
; ;
; RETURNED: status: ;
; is the status EMM returns from the call. All other ;
; returned results are valid only if the status ;
; returned is zero. Otherwise they are undefined. ;
; ;
; The SOURCE memory region described by: ;
; ms.source_handle ;
; ms.source_init_offset ;
; ms.source_init_log_page_or_seg ;
; is MOVED into the DESTINATION memory region: ;
; ms.dest_handle ;
; ms.dest_init_offset ;
; ms.dest_init_log_page_or_seg ;
; ;
; C USE CONVENTION: unsigned int status; ;
; MOVE_XCHG_STRUCT ms; ;
; ;
; ms.region_size = 640 * 1024; ;
; ms.source_mem_type = CONV_MEM; ;
; ms.source_handle = 0; ;
; ms.source_init_log_page_or_seg = 0x0000; ;
; ms.source_init_offset = 0x0000; ;
; ms.dest_mem_type = EXP_MEM; ;
; ms.dest_handle = 1; ;
; ms.dest_init_log_page_or_seg = 0; ;
; ms.dest_init_offset = 0x0000; ;
; ;
; status = move_memory_region (&ms); ;
;-----------------------------------------------------------------------------;
.XLIST
PAGE 60,132
IFDEF SMALL
.MODEL SMALL, C
ENDIF
IFDEF MEDIUM
.MODEL MEDIUM, C
ENDIF
IFDEF LARGE
.MODEL LARGE, C
ENDIF
IFDEF COMPACT
.MODEL COMPACT, C
ENDIF
IFDEF HUGE
.MODEL HUGE, C
ENDIF
INCLUDE emmlib.equ
INCLUDE emmlib.str
INCLUDE emmlib.mac
.LIST
.CODE
move_memory_region PROC \
USES DS SI, \
ptr_move_struct:FAR PTR BYTE
;---------------------------------------------------------------------;
; do; ;
; . move the contents of a source memory region to a destination ;
; . memory region; ;
;---------------------------------------------------------------------;
MOVE AX, move_memory_fcn
MOVE DS:SI, ptr_move_struct
INT EMM_int
;---------------------------------------------------------------------;
; . return (EMM status); ;
; end; ;
;---------------------------------------------------------------------;
RET_EMM_STAT AH
move_memory_region ENDP
END