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annotate mem.c @ 1385:1eded4f19910

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Prevent emulated screen from "rolling" when the vertical resolution is changed at an inopportune time
author Michael Pavone <pavone@retrodev.com>
date Wed, 31 May 2017 21:10:49 -0700
parents 101b5ce682fe
children 8e86cd581620
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1 /*
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2 Copyright 2013 Michael Pavone
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3 This file is part of BlastEm.
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4 BlastEm is free software distributed under the terms of the GNU General Public License version 3 or greater. See COPYING for full license text.
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5 */
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6 #include <sys/mman.h>
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7 #include <stddef.h>
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8 #include <stdint.h>
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9 #include <stdlib.h>
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10 #include <unistd.h>
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11 #include <errno.h>
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12 #include <stdio.h>
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14 #include "mem.h"
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15 #include "arena.h"
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16 #ifndef MAP_ANONYMOUS
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17 #define MAP_ANONYMOUS MAP_ANON
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18 #endif
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20 #ifndef MAP_32BIT
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21 #define MAP_32BIT 0
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22 #endif
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24 void * alloc_code(size_t *size)
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25 {
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26 //start at the 1GB mark to allow plenty of room for sbrk based malloc implementations
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27 //while still keeping well within 32-bit displacement range for calling code compiled into the executable
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28 static uint8_t *next = (uint8_t *)0x40000000;
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29 uint8_t *ret = try_alloc_arena();
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30 if (ret) {
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31 return ret;
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32 }
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33 if (*size & (PAGE_SIZE -1)) {
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34 *size += PAGE_SIZE - (*size & (PAGE_SIZE - 1));
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35 }
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36 ret = mmap(next, *size, PROT_EXEC | PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_32BIT, -1, 0);
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37 if (ret == MAP_FAILED) {
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38 perror("alloc_code");
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39 return NULL;
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40 }
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41 track_block(ret);
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42 next = ret + *size;
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43 return ret;
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44 }
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