94 lines
2.0 KiB
C
94 lines
2.0 KiB
C
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#ifdef __CYGWIN__
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#include <sys/mman.h>
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#include <stdio.h>
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#include <strings.h>
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#include <errno.h>
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#include <assert.h>
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#define pagesize 4096
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#define pageshift 12
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#define segment_size (16*pagesize)
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#define segment_shift (4+pageshift)
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#include "winmmap.h"
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/* vim:syntax=c */
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static unsigned short* table = 0;
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static char* ap = 0;
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static size_t as = 0;
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static void*
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do_mmap(size_t n){
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void* x = mmap(0, n, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0);
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if(x == (void*)-1){
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fprintf(stderr, "failed to mmap: %s\n", strerror(errno));
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exit(-1);
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}
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assert((((unsigned int)x) & (segment_size-1)) == 0);
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return x;
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}
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static void
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do_munmap(void* addr, size_t size){
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int err = munmap(addr, size);
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if(err){
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fprintf(stderr, "failed to unmap\n");
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exit(-1);
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}
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}
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static void
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init_table(){
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assert(sizeof(unsigned short) == 2);
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table = do_mmap(32*pagesize);
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bzero(table, 32*pagesize);
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}
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void
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win_munmap(char* addr, size_t size){
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while(size){
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unsigned int page = (((unsigned int) addr) >> pageshift);
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unsigned int segment_index = page / 16;
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unsigned int page_index = page & 15;
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unsigned short alloc_bits = table[segment_index];
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assert((alloc_bits & (1<<page_index)) == (1<<page_index));
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unsigned int new_bits = alloc_bits & ~ (1 << page_index);
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table[segment_index] = new_bits;
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if(new_bits == 0){
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do_munmap((void*)(segment_index*segment_size), segment_size);
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}
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size -= pagesize;
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addr += pagesize;
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}
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}
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char*
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win_mmap(size_t size){
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if(size <= as){
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char* x = ap;
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ap += size;
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as -= size;
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return x;
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}
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if(table == 0) init_table();
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win_munmap(ap, as);
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size_t segments = ((size+segment_size-1) >> segment_shift);
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size_t aligned_size = segments << segment_shift;
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char* addr = do_mmap(aligned_size);
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unsigned int page = (((unsigned int) addr) >> pageshift);
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unsigned int segment_index = page / 16;
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int i;
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for(i=0; i<segments; i++){
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table[segment_index+i] = -1;
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}
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ap = addr + size;
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as = aligned_size - size;
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return addr;
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}
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#endif
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