/* * jvirtmem.c * * Copyright (C) 1991, Thomas G. Lane. * This file is part of the Independent JPEG Group's software. * For conditions of distribution and use, see the accompanying README file. * * This file provides the system-dependent memory allocation routines * for the case where we can rely on virtual memory to handle large arrays. * * This includes some MS-DOS code just for trial purposes; "big" arrays will * have to be handled with temp files on MS-DOS, so a real implementation of * a DOS memory manager will probably be a separate file. (See additional * comments about big arrays, below.) * * NB: allocation routines never return NULL. * They should exit to error_exit if unsuccessful. */ #include "jinclude.h" #ifdef __STDC__ #include /* to declare malloc(), free() */ #else extern void * malloc PP((size_t size)); extern void free PP((void *ptr)); #endif /* Insert system-specific definitions of far_malloc, far_free here. */ #ifndef NEED_FAR_POINTERS /* Generic for non-braindamaged CPUs */ #define far_malloc(x) malloc(x) #define far_free(x) free(x) #else /* NEED_FAR_POINTERS */ #ifdef __TURBOC__ /* These definitions work for Turbo C */ #include /* need farmalloc(), farfree() */ #define far_malloc(x) farmalloc(x) #define far_free(x) farfree(x) #else #ifdef MSDOS /* These definitions work for Microsoft C and compatible compilers */ #include /* need _fmalloc(), _ffree() */ #define far_malloc(x) _fmalloc(x) #define far_free(x) _ffree(x) #endif #endif #endif /* NEED_FAR_POINTERS */ /* * Some important notes: * The array alloc/dealloc routines are not merely a convenience; * on 80x86 machines the bottom-level pointers in an array are FAR * and thus may not be allocatable by alloc_small. * * Also, it's not a good idea to try to merge the sarray and barray * routines, even though they are textually almost the same, because * samples are usually stored as bytes while coefficients are shorts. * Thus, in machines where byte pointers have a different representation * from word pointers, the resulting machine code could not be the same. */ static external_methods_ptr methods; /* saved for access to error_exit */ #ifdef MEM_STATS /* optional extra stuff for statistics */ #define MALLOC_OVERHEAD (SIZEOF(char *)) /* assumed overhead per request */ #define MALLOC_FAR_OVERHEAD (SIZEOF(char FAR *)) /* for "far" storage */ static long total_num_small = 0; /* total # of small objects alloced */ static long total_bytes_small = 0; /* total bytes requested */ static long cur_num_small = 0; /* # currently alloced */ static long max_num_small = 0; /* max simultaneously alloced */ #ifdef NEED_FAR_POINTERS static long total_num_medium = 0; /* total # of medium objects alloced */ static long total_bytes_medium = 0; /* total bytes requested */ static long cur_num_medium = 0; /* # currently alloced */ static long max_num_medium = 0; /* max simultaneously alloced */ #endif static long total_num_sarray = 0; /* total # of sarray objects alloced */ static long total_bytes_sarray = 0; /* total bytes requested */ static long cur_num_sarray = 0; /* # currently alloced */ static long max_num_sarray = 0; /* max simultaneously alloced */ static long total_num_barray = 0; /* total # of barray objects alloced */ static long total_bytes_barray = 0; /* total bytes requested */ static long cur_num_barray = 0; /* # currently alloced */ static long max_num_barray = 0; /* max simultaneously alloced */ GLOBAL void j_mem_stats (void) { /* since this is only a debugging stub, we can cheat a little on the * trace message mechanism... helps 'cuz trace can't handle longs. */ fprintf(stderr, "total_num_small = %ld\n", total_num_small); fprintf(stderr, "total_bytes_small = %ld\n", total_bytes_small); if (cur_num_small) fprintf(stderr, "CUR_NUM_SMALL = %ld\n", cur_num_small); fprintf(stderr, "max_num_small = %ld\n", max_num_small); #ifdef NEED_FAR_POINTERS fprintf(stderr, "total_num_medium = %ld\n", total_num_medium); fprintf(stderr, "total_bytes_medium = %ld\n", total_bytes_medium); if (cur_num_medium) fprintf(stderr, "CUR_NUM_MEDIUM = %ld\n", cur_num_medium); fprintf(stderr, "max_num_medium = %ld\n", max_num_medium); #endif fprintf(stderr, "total_num_sarray = %ld\n", total_num_sarray); fprintf(stderr, "total_bytes_sarray = %ld\n", total_bytes_sarray); if (cur_num_sarray) fprintf(stderr, "CUR_NUM_SARRAY = %ld\n", cur_num_sarray); fprintf(stderr, "max_num_sarray = %ld\n", max_num_sarray); fprintf(stderr, "total_num_barray = %ld\n", total_num_barray); fprintf(stderr, "total_bytes_barray = %ld\n", total_bytes_barray); if (cur_num_barray) fprintf(stderr, "CUR_NUM_BARRAY = %ld\n", cur_num_barray); fprintf(stderr, "max_num_barray = %ld\n", max_num_barray); } #endif /* MEM_STATS */ LOCAL void out_of_memory (int which) /* Report an out-of-memory error and stop execution */ /* If we compiled MEM_STATS support, report alloc requests before dying */ { #ifdef MEM_STATS j_mem_stats(); #endif ERREXIT1(methods, "Insufficient memory (case %d)", which); } METHODDEF void * alloc_small (size_t sizeofobject) /* Allocate a "small" (all-in-memory) object */ { void * result; #ifdef MEM_STATS total_num_small++; total_bytes_small += sizeofobject + MALLOC_OVERHEAD; cur_num_small++; if (cur_num_small > max_num_small) max_num_small = cur_num_small; #endif result = malloc(sizeofobject); if (result == NULL) out_of_memory(1); return result; } METHODDEF void free_small (void *ptr) /* Free a "small" (all-in-memory) object */ { free(ptr); #ifdef MEM_STATS cur_num_small--; #endif } #ifdef NEED_FAR_POINTERS METHODDEF void FAR * alloc_medium (size_t sizeofobject) /* Allocate a "medium" (all in memory, but in far heap) object */ { void FAR * result; #ifdef MEM_STATS total_num_medium++; total_bytes_medium += sizeofobject + MALLOC_FAR_OVERHEAD; cur_num_medium++; if (cur_num_medium > max_num_medium) max_num_medium = cur_num_medium; #endif result = far_malloc(sizeofobject); if (result == NULL) out_of_memory(2); return result; } METHODDEF void free_medium (void FAR *ptr) /* Free a "medium" (all in memory, but in far heap) object */ { far_free(ptr); #ifdef MEM_STATS cur_num_medium--; #endif } #endif /* NEED_FAR_POINTERS */ METHODDEF JSAMPARRAY alloc_small_sarray (long samplesperrow, long numrows) /* Allocate a "small" (all-in-memory) 2-D sample array */ { JSAMPARRAY result; long i; #ifdef MEM_STATS total_num_sarray++; total_bytes_sarray += (samplesperrow * SIZEOF(JSAMPLE) + MALLOC_FAR_OVERHEAD) * numrows; cur_num_sarray++; if (cur_num_sarray > max_num_sarray) max_num_sarray = cur_num_sarray; #endif /* Get space for row pointers; this is always "near" on 80x86 */ result = (JSAMPARRAY) alloc_small((size_t) (numrows * SIZEOF(JSAMPROW))); /* Get the rows themselves; on 80x86 these are "far" */ for (i = 0; i < numrows; i++) { result[i] = (JSAMPROW) far_malloc((size_t) (samplesperrow * SIZEOF(JSAMPLE))); if (result[i] == NULL) out_of_memory(3); } return result; } METHODDEF void free_small_sarray (JSAMPARRAY ptr, long numrows) /* Free a "small" (all-in-memory) 2-D sample array */ { long i; /* Free the rows themselves; on 80x86 these are "far" */ for (i = 0; i < numrows; i++) { far_free((void FAR *) ptr[i]); } /* Free space for row pointers; this is always "near" on 80x86 */ free_small((void *) ptr); #ifdef MEM_STATS cur_num_sarray--; #endif } METHODDEF JBLOCKARRAY alloc_small_barray (long blocksperrow, long numrows) /* Allocate a "small" (all-in-memory) 2-D coefficient-block array */ { JBLOCKARRAY result; long i; #ifdef MEM_STATS total_num_barray++; total_bytes_barray += (blocksperrow * SIZEOF(JBLOCK) + MALLOC_FAR_OVERHEAD) * numrows; cur_num_barray++; if (cur_num_barray > max_num_barray) max_num_barray = cur_num_barray; #endif /* Get space for row pointers; this is always "near" on 80x86 */ result = (JBLOCKARRAY) alloc_small((size_t) (numrows * SIZEOF(JBLOCKROW))); /* Get the rows themselves; on 80x86 these are "far" */ for (i = 0; i < numrows; i++) { result[i] = (JBLOCKROW) far_malloc((size_t) (blocksperrow * SIZEOF(JBLOCK))); if (result[i] == NULL) out_of_memory(4); } return result; } METHODDEF void free_small_barray (JBLOCKARRAY ptr, long numrows) /* Free a "small" (all-in-memory) 2-D coefficient-block array */ { long i; /* Free the rows themselves; on 80x86 these are "far" */ for (i = 0; i < numrows; i++) { far_free((void FAR *) ptr[i]); } /* Free space for row pointers; this is always "near" on 80x86 */ free_small((void *) ptr); #ifdef MEM_STATS cur_num_barray--; #endif } /* * About "big" array management: * * To allow machines with limited memory to handle large images, * all processing in the JPEG system is done a few pixel or block rows * at a time. The above "small" array routines are only used to allocate * strip buffers (as wide as the image, but just a few rows high). * In some cases multiple passes must be made over the data. In these * cases the "big" array routines are used. The array is still accessed * a strip at a time, but the memory manager must save the whole array * for repeated accesses. The intended implementation is that there is * a strip buffer in memory (as high as is possible given the desired memory * limit), plus a backing file that holds the rest of the array. * * The request_big_array routines are told the total size of the image (in case * it is useful to know the total file size that will be needed). They are * also given the unit height, which is the number of rows that will be * accessed at once; the in-memory buffer should usually be made a multiple of * this height for best efficiency. * * The request routines create control blocks (and may open backing files), * but they don't create the in-memory buffers. This is postponed until * alloc_big_arrays is called. At that time the total amount of space needed * is known (approximately, anyway), so free memory can be divided up fairly. * * The access_big_array routines are responsible for making a specific strip * area accessible (after reading or writing the backing file, if necessary). * Note that the access routines are told whether the caller intends to modify * the accessed strip; during a read-only pass this saves having to rewrite * data to disk. * * The typical access pattern is one top-to-bottom pass to write the data, * followed by one or more read-only top-to-bottom passes. However, other * access patterns may occur while reading. For example, translation of image * formats that use bottom-to-top scan order will require bottom-to-top read * passes. The memory manager need not support multiple write passes nor * funny write orders (meaning that rearranging rows must be handled while * reading data out of the big array, not while putting it in). * * In current usage, the access requests are always for nonoverlapping strips; * that is, successive access start_row numbers always differ by exactly the * unitheight. This allows fairly simple buffer dump/reload logic if the * in-memory buffer is made a multiple of the unitheight. It would be * possible to keep subsampled rather than fullsize data in the "big" arrays, * thus reducing temp file size, if we supported overlapping strip access * (access requests differing by less than the unitheight). At the moment * I don't believe this is worth the extra complexity. * * This particular implementation doesn't use temp files; the whole of a big * array is allocated in (virtual) memory, and any swapping is done behind the * scenes by the operating system. */ /* The control blocks for virtual arrays. * These are pretty minimal in this implementation. * Note: in this implementation we could realize big arrays * at request time and make alloc_big_arrays a no-op; * however, doing it separately keeps callers honest. */ struct big_sarray_control { JSAMPARRAY mem_buffer; /* memory buffer (the whole thing, here) */ long rows_in_mem; /* Height of memory buffer */ long samplesperrow; /* Width of memory buffer */ long unitheight; /* # of rows accessed by access_big_sarray() */ big_sarray_ptr next; /* list link for unrealized arrays */ }; struct big_barray_control { JBLOCKARRAY mem_buffer; /* memory buffer (the whole thing, here) */ long rows_in_mem; /* Height of memory buffer */ long blocksperrow; /* Width of memory buffer */ long unitheight; /* # of rows accessed by access_big_barray() */ big_barray_ptr next; /* list link for unrealized arrays */ }; /* Headers of lists of control blocks for unrealized big arrays */ static big_sarray_ptr unalloced_sarrays; static big_barray_ptr unalloced_barrays; METHODDEF big_sarray_ptr request_big_sarray (long samplesperrow, long numrows, long unitheight) /* Request a "big" (virtual-memory) 2-D sample array */ { big_sarray_ptr result; /* get control block */ result = (big_sarray_ptr) alloc_small(SIZEOF(struct big_sarray_control)); result->mem_buffer = NULL; /* lets access routine spot premature access */ result->rows_in_mem = numrows; result->samplesperrow = samplesperrow; result->unitheight = unitheight; result->next = unalloced_sarrays; /* add to list of unallocated arrays */ unalloced_sarrays = result; return result; } METHODDEF big_barray_ptr request_big_barray (long blocksperrow, long numrows, long unitheight) /* Request a "big" (virtual-memory) 2-D coefficient-block array */ { big_barray_ptr result; /* get control block */ result = (big_barray_ptr) alloc_small(SIZEOF(struct big_barray_control)); result->mem_buffer = NULL; /* lets access routine spot premature access */ result->rows_in_mem = numrows; result->blocksperrow = blocksperrow; result->unitheight = unitheight; result->next = unalloced_barrays; /* add to list of unallocated arrays */ unalloced_barrays = result; return result; } METHODDEF void alloc_big_arrays (long extra_small_samples, long extra_small_blocks, long extra_medium_space) /* Allocate the in-memory buffers for any unrealized "big" arrays */ /* 'extra' values are upper bounds for total future small-array requests */ /* and far-heap requests */ { /* In this implementation we just malloc the whole arrays */ /* and expect the system's virtual memory to worry about swapping them */ big_sarray_ptr sptr; big_barray_ptr bptr; for (sptr = unalloced_sarrays; sptr != NULL; sptr = sptr->next) { sptr->mem_buffer = alloc_small_sarray(sptr->samplesperrow, sptr->rows_in_mem); } for (bptr = unalloced_barrays; bptr != NULL; bptr = bptr->next) { bptr->mem_buffer = alloc_small_barray(bptr->blocksperrow, bptr->rows_in_mem); } unalloced_sarrays = NULL; /* reset for possible future cycles */ unalloced_barrays = NULL; } METHODDEF JSAMPARRAY access_big_sarray (big_sarray_ptr ptr, long start_row, boolean writable) /* Access the part of a "big" sample array starting at start_row */ /* and extending for ptr->unitheight rows. writable is true if */ /* caller intends to modify the accessed area. */ { /* debugging check */ if (start_row < 0 || start_row+ptr->unitheight > ptr->rows_in_mem || ptr->mem_buffer == NULL) ERREXIT(methods, "Bogus access_big_sarray request"); return ptr->mem_buffer + start_row; } METHODDEF JBLOCKARRAY access_big_barray (big_barray_ptr ptr, long start_row, boolean writable) /* Access the part of a "big" coefficient-block array starting at start_row */ /* and extending for ptr->unitheight rows. writable is true if */ /* caller intends to modify the accessed area. */ { /* debugging check */ if (start_row < 0 || start_row+ptr->unitheight > ptr->rows_in_mem || ptr->mem_buffer == NULL) ERREXIT(methods, "Bogus access_big_barray request"); return ptr->mem_buffer + start_row; } METHODDEF void free_big_sarray (big_sarray_ptr ptr) /* Free a "big" (virtual-memory) 2-D sample array */ { free_small_sarray(ptr->mem_buffer, ptr->rows_in_mem); free_small((void *) ptr); /* free the control block too */ } METHODDEF void free_big_barray (big_barray_ptr ptr) /* Free a "big" (virtual-memory) 2-D coefficient-block array */ { free_small_barray(ptr->mem_buffer, ptr->rows_in_mem); free_small((void *) ptr); /* free the control block too */ } /* * The method selection routine for virtual memory systems. * The system-dependent setup routine should call this routine * to install the necessary method pointers in the supplied struct. */ GLOBAL void jselvirtmem (external_methods_ptr emethods) { methods = emethods; /* save struct addr for error exit access */ emethods->alloc_small = alloc_small; emethods->free_small = free_small; #ifdef NEED_FAR_POINTERS emethods->alloc_medium = alloc_medium; emethods->free_medium = free_medium; #endif emethods->alloc_small_sarray = alloc_small_sarray; emethods->free_small_sarray = free_small_sarray; emethods->alloc_small_barray = alloc_small_barray; emethods->free_small_barray = free_small_barray; emethods->request_big_sarray = request_big_sarray; emethods->request_big_barray = request_big_barray; emethods->alloc_big_arrays = alloc_big_arrays; emethods->access_big_sarray = access_big_sarray; emethods->access_big_barray = access_big_barray; emethods->free_big_sarray = free_big_sarray; emethods->free_big_barray = free_big_barray; unalloced_sarrays = NULL; /* make sure list headers are empty */ unalloced_barrays = NULL; }