221 lines
4.4 KiB
C
221 lines
4.4 KiB
C
/*
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* memory.c
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*
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* PSXSDK malloc() family functions
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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extern int __bss_start[];
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extern int __bss_end[];
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static unsigned int first_free_page;
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static int init;
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// 1K granularity and "pages", so more allocations which are small can be done
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static unsigned char busy_pages[2048];
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static unsigned int alloc_size[2048];
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// RAM memory map on the PSX
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// 0x80000000 - 0x8000FFFF RAM used by the BIOS
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// 0x80010000 - 0x801FFFFF Program memory
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static void malloc_setup()
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{
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int x;
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dprintf("malloc setup.\n");
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first_free_page = (unsigned int) __bss_end;
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first_free_page-= 0x80000000;
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if(first_free_page & 0x3ff)
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first_free_page = (first_free_page | 0x3ff) + 1;
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first_free_page>>=10;
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//printf("First free page: %d, bss_end: %x\n", first_free_page, __bss_end);
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for(x = 0; x < first_free_page; x++)
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{
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busy_pages[x] = 1; // RAM occupied by program, data and BIOS looks always allocated
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alloc_size[x] = 1; // Fake that 1K was required
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}
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for(x = first_free_page; x < 2048; x++)
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{
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busy_pages[x] = 0;
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alloc_size[x] = 0;
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}
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}
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void *malloc(size_t size)
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{
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if (!init)
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{
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// Setup memory allocation functions
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malloc_setup();
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dprintf("Finished setting up memory allocation functions.\n");
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init = 1;
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}
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dprintf("malloc(%d)\n", size);
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int x, y;
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// Round size
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if(size & 0x3ff)
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size = (size | 0x3ff) + 1;
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// Divide it by 1024
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size >>= 10;
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//printf("Allocating %dKb\n", size);
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// Find a free page
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for(x = 0; x < 2048; x++)
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{
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if(busy_pages[x] == 0)
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{
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// If we find a free page, check how many free pages follow it.
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// If it's enough for the memory we want to allocate, then return
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// the pointer to the free page we found, otherwise keep finding
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// printf("Page found at %dKb\n", x);
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for(y = 0; y < size; y++)
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if(busy_pages[x+y] == 1) continue;
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// We found the memory we wanted, now make it busy
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for(y = 0; y < size; y++)
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busy_pages[x+y] = 1;
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// Store allocation size, it is essential for free()
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alloc_size[x] = size;
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// printf("malloc(): alloc_size[%d] = %d\n", x, size);
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printf("finished malloc(%d)\n", size);
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return (void*)((unsigned int)0x80000000 + (x<<10));
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}
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}
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printf("failed malloc(%d)\n", size);
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// We couldn't find anything, return NULL
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return NULL;
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}
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void *calloc(size_t number, size_t size)
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{
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void *ptr = malloc(number * size);
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if (ptr)
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memset(ptr, 0, number * size);
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return ptr;
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}
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void free(void *ptr)
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{
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dprintf("free(%x)\n", (unsigned int)ptr);
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unsigned int ptri = (unsigned int)ptr;
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ptri -= 0x80000000;
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int x;
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if((ptri & 0x3ff) || (busy_pages[ptri>>10] == 0) || (alloc_size[ptri>>10] == 0))
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{
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// If the pointer address is not a multiplier of 1K, or the page
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// is free, it means that memory not allocated by malloc() was passed to free.
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// Print a warning message and return.
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printf("** free() ** : tried to free memory with invalid pointer at %x\n",
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ptri + 0x80000000);
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return;
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}
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// Divide ptri by 1024, getting initial page
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ptri>>=10;
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// printf("Freeing page at %dKb\n", ptri);
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// Free pages
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// printf("alloc_size[%d] = %d\n", ptri, alloc_size[ptri]);
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for(x = 0; x < alloc_size[ptri]; x++)
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{
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dprintf("ptri + x = %d\n", ptri + x);
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busy_pages[ptri + x] = 0;
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}
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// Set allocation size to 0, finally freeing initial page
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alloc_size[ptri] = 0;
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/*for(x=150;x<170;x++)
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printf("%d: %d, %d\n", x, busy_pages[x], alloc_size[x]);*/
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}
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void *realloc(void *ptr, size_t size)
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{
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unsigned int ptri = (unsigned int)ptr;
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int x;
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void *newptr;
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if(ptr == NULL)
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return malloc(size);
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ptri -= 0x80000000;
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size |= 0x3ff;
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size++;
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size>>=10;
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if((ptri & 0x3ff) || (busy_pages[ptri>>10] == 0) || (alloc_size[ptri>>10] == 0))
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{
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// If the pointer address is not a multiplier of 1K, or the page
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// is free, it means that memory not allocated by malloc() was passed to realloc.
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// Print a warning message and return.
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printf("** realloc() ** : tried to reallocate memory with invalid pointer at %x\n",
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ptri + 0x80000000);
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return NULL;
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}
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// Get page
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ptri>>=10;
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if(size < alloc_size[ptri]) // New size smaller than old size
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{
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for(x = size; x < alloc_size[ptri]; x++)
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busy_pages[ptri + x] = 0;
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alloc_size[ptri] = size;
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}
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else if(size > alloc_size[ptri]) // New size bigger than old size
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{
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newptr = malloc(size * 1024);
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if(newptr == NULL)
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return NULL;
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memcpy(newptr, ptr, alloc_size[ptri]);
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free(ptr);
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ptr = newptr;
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}
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return ptr;
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}
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