You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
259 lines
9.2 KiB
259 lines
9.2 KiB
unit imjmemnobs;
|
|
{ Delphi3 -- > jmemnobs from jmemwin }
|
|
{ This file provides an Win32-compatible implementation of the system-
|
|
dependent portion of the JPEG memory manager. }
|
|
|
|
{ Check jmemnobs.c }
|
|
{ Copyright (C) 1996, Jacques Nomssi Nzali }
|
|
|
|
|
|
interface
|
|
|
|
{$I imjconfig.inc}
|
|
|
|
uses
|
|
imjmorecfg,
|
|
imjdeferr,
|
|
imjerror,
|
|
imjpeglib;
|
|
|
|
{ The macro MAX_ALLOC_CHUNK designates the maximum number of bytes that may
|
|
be requested in a single call to jpeg_get_large (and jpeg_get_small for that
|
|
matter, but that case should never come into play). This macro is needed
|
|
to model the 64Kb-segment-size limit of far addressing on 80x86 machines.
|
|
On those machines, we expect that jconfig.h will provide a proper value.
|
|
On machines with 32-bit flat address spaces, any large constant may be used.
|
|
|
|
NB: jmemmgr.c expects that MAX_ALLOC_CHUNK will be representable as type
|
|
size_t and will be a multiple of sizeof(align_type). }
|
|
|
|
const
|
|
MAX_ALLOC_CHUNK = long(1000000000);
|
|
|
|
{GLOBAL}
|
|
procedure jpeg_open_backing_store (cinfo : j_common_ptr;
|
|
info : backing_store_ptr;
|
|
total_bytes_needed : long);
|
|
|
|
{ These routines take care of any system-dependent initialization and
|
|
cleanup required. }
|
|
|
|
{GLOBAL}
|
|
function jpeg_mem_init (cinfo : j_common_ptr) : long;
|
|
|
|
{GLOBAL}
|
|
procedure jpeg_mem_term (cinfo : j_common_ptr);
|
|
|
|
{ These two functions are used to allocate and release small chunks of
|
|
memory. (Typically the total amount requested through jpeg_get_small is
|
|
no more than 20K or so; this will be requested in chunks of a few K each.)
|
|
Behavior should be the same as for the standard library functions malloc
|
|
and free; in particular, jpeg_get_small must return NIL on failure.
|
|
On most systems, these ARE malloc and free. jpeg_free_small is passed the
|
|
size of the object being freed, just in case it's needed.
|
|
On an 80x86 machine using small-data memory model, these manage near heap. }
|
|
|
|
|
|
{ Near-memory allocation and freeing are controlled by the regular library
|
|
routines malloc() and free(). }
|
|
|
|
{GLOBAL}
|
|
function jpeg_get_small (cinfo : j_common_ptr;
|
|
sizeofobject : size_t) : pointer;
|
|
|
|
{GLOBAL}
|
|
{object is a reserved word in Borland Pascal }
|
|
procedure jpeg_free_small (cinfo : j_common_ptr;
|
|
an_object : pointer;
|
|
sizeofobject : size_t);
|
|
|
|
{ These two functions are used to allocate and release large chunks of
|
|
memory (up to the total free space designated by jpeg_mem_available).
|
|
The interface is the same as above, except that on an 80x86 machine,
|
|
far pointers are used. On most other machines these are identical to
|
|
the jpeg_get/free_small routines; but we keep them separate anyway,
|
|
in case a different allocation strategy is desirable for large chunks. }
|
|
|
|
|
|
{ "Large" objects are allocated in far memory, if possible }
|
|
|
|
|
|
{GLOBAL}
|
|
function jpeg_get_large (cinfo : j_common_ptr;
|
|
sizeofobject : size_t) : voidp; {far}
|
|
|
|
{GLOBAL}
|
|
procedure jpeg_free_large (cinfo : j_common_ptr;
|
|
{var?} an_object : voidp; {FAR}
|
|
sizeofobject : size_t);
|
|
|
|
{ This routine computes the total memory space available for allocation.
|
|
It's impossible to do this in a portable way; our current solution is
|
|
to make the user tell us (with a default value set at compile time).
|
|
If you can actually get the available space, it's a good idea to subtract
|
|
a slop factor of 5% or so. }
|
|
|
|
{GLOBAL}
|
|
function jpeg_mem_available (cinfo : j_common_ptr;
|
|
min_bytes_needed : long;
|
|
max_bytes_needed : long;
|
|
already_allocated : long) : long;
|
|
|
|
|
|
implementation
|
|
|
|
{ This structure holds whatever state is needed to access a single
|
|
backing-store object. The read/write/close method pointers are called
|
|
by jmemmgr.c to manipulate the backing-store object; all other fields
|
|
are private to the system-dependent backing store routines. }
|
|
|
|
|
|
|
|
{ These two functions are used to allocate and release small chunks of
|
|
memory. (Typically the total amount requested through jpeg_get_small is
|
|
no more than 20K or so; this will be requested in chunks of a few K each.)
|
|
Behavior should be the same as for the standard library functions malloc
|
|
and free; in particular, jpeg_get_small must return NIL on failure.
|
|
On most systems, these ARE malloc and free. jpeg_free_small is passed the
|
|
size of the object being freed, just in case it's needed.
|
|
On an 80x86 machine using small-data memory model, these manage near heap. }
|
|
|
|
|
|
{ Near-memory allocation and freeing are controlled by the regular library
|
|
routines malloc() and free(). }
|
|
|
|
{GLOBAL}
|
|
function jpeg_get_small (cinfo : j_common_ptr;
|
|
sizeofobject : size_t) : pointer;
|
|
var
|
|
p : pointer;
|
|
begin
|
|
GetMem(p, sizeofobject);
|
|
jpeg_get_small := p;
|
|
end;
|
|
|
|
{GLOBAL}
|
|
{object is a reserved word in Object Pascal }
|
|
procedure jpeg_free_small (cinfo : j_common_ptr;
|
|
an_object : pointer;
|
|
sizeofobject : size_t);
|
|
begin
|
|
FreeMem(an_object, sizeofobject);
|
|
end;
|
|
|
|
{ These two functions are used to allocate and release large chunks of
|
|
memory (up to the total free space designated by jpeg_mem_available).
|
|
The interface is the same as above, except that on an 80x86 machine,
|
|
far pointers are used. On most other machines these are identical to
|
|
the jpeg_get/free_small routines; but we keep them separate anyway,
|
|
in case a different allocation strategy is desirable for large chunks. }
|
|
|
|
|
|
|
|
{GLOBAL}
|
|
function jpeg_get_large (cinfo : j_common_ptr;
|
|
sizeofobject : size_t) : voidp; {far}
|
|
var
|
|
p : pointer;
|
|
begin
|
|
GetMem(p, sizeofobject);
|
|
jpeg_get_large := p;
|
|
end;
|
|
|
|
{GLOBAL}
|
|
procedure jpeg_free_large (cinfo : j_common_ptr;
|
|
{var?} an_object : voidp; {FAR}
|
|
sizeofobject : size_t);
|
|
begin
|
|
Freemem(an_object, sizeofobject);
|
|
end;
|
|
|
|
{ This routine computes the total space still available for allocation by
|
|
jpeg_get_large. If more space than this is needed, backing store will be
|
|
used. NOTE: any memory already allocated must not be counted.
|
|
|
|
There is a minimum space requirement, corresponding to the minimum
|
|
feasible buffer sizes; jmemmgr.c will request that much space even if
|
|
jpeg_mem_available returns zero. The maximum space needed, enough to hold
|
|
all working storage in memory, is also passed in case it is useful.
|
|
Finally, the total space already allocated is passed. If no better
|
|
method is available, cinfo^.mem^.max_memory_to_use - already_allocated
|
|
is often a suitable calculation.
|
|
|
|
It is OK for jpeg_mem_available to underestimate the space available
|
|
(that'll just lead to more backing-store access than is really necessary).
|
|
However, an overestimate will lead to failure. Hence it's wise to subtract
|
|
a slop factor from the true available space. 5% should be enough.
|
|
|
|
On machines with lots of virtual memory, any large constant may be returned.
|
|
Conversely, zero may be returned to always use the minimum amount of memory.}
|
|
|
|
|
|
|
|
{ This routine computes the total memory space available for allocation.
|
|
It's impossible to do this in a portable way; our current solution is
|
|
to make the user tell us (with a default value set at compile time).
|
|
If you can actually get the available space, it's a good idea to subtract
|
|
a slop factor of 5% or so. }
|
|
|
|
const
|
|
DEFAULT_MAX_MEM = long(300000); { for total usage about 450K }
|
|
|
|
{GLOBAL}
|
|
function jpeg_mem_available (cinfo : j_common_ptr;
|
|
min_bytes_needed : long;
|
|
max_bytes_needed : long;
|
|
already_allocated : long) : long;
|
|
begin
|
|
{jpeg_mem_available := cinfo^.mem^.max_memory_to_use - already_allocated;}
|
|
jpeg_mem_available := max_bytes_needed;
|
|
end;
|
|
|
|
|
|
{ Initial opening of a backing-store object. This must fill in the
|
|
read/write/close pointers in the object. The read/write routines
|
|
may take an error exit if the specified maximum file size is exceeded.
|
|
(If jpeg_mem_available always returns a large value, this routine can
|
|
just take an error exit.) }
|
|
|
|
|
|
|
|
{ Initial opening of a backing-store object. }
|
|
|
|
{GLOBAL}
|
|
procedure jpeg_open_backing_store (cinfo : j_common_ptr;
|
|
info : backing_store_ptr;
|
|
total_bytes_needed : long);
|
|
begin
|
|
ERREXIT(cinfo, JERR_NO_BACKING_STORE);
|
|
end;
|
|
|
|
{ These routines take care of any system-dependent initialization and
|
|
cleanup required. jpeg_mem_init will be called before anything is
|
|
allocated (and, therefore, nothing in cinfo is of use except the error
|
|
manager pointer). It should return a suitable default value for
|
|
max_memory_to_use; this may subsequently be overridden by the surrounding
|
|
application. (Note that max_memory_to_use is only important if
|
|
jpeg_mem_available chooses to consult it ... no one else will.)
|
|
jpeg_mem_term may assume that all requested memory has been freed and that
|
|
all opened backing-store objects have been closed. }
|
|
|
|
|
|
{ These routines take care of any system-dependent initialization and
|
|
cleanup required. }
|
|
|
|
|
|
{GLOBAL}
|
|
function jpeg_mem_init (cinfo : j_common_ptr) : long;
|
|
begin
|
|
jpeg_mem_init := DEFAULT_MAX_MEM; { default for max_memory_to_use }
|
|
end;
|
|
|
|
{GLOBAL}
|
|
procedure jpeg_mem_term (cinfo : j_common_ptr);
|
|
begin
|
|
|
|
end;
|
|
|
|
|
|
end.
|