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memory.c
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memory.c
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/* �������W */
#include "bootpack.h"
#define EFLAGS_AC_BIT 0x00040000
#define CR0_CACHE_DISABLE 0x60000000
unsigned int memtest(unsigned int start, unsigned int end)
{
char flg486 = 0;
unsigned int eflg, cr0, i;
/* 确认CPU是386还是486以上的 */
eflg = io_load_eflags();
eflg |= EFLAGS_AC_BIT; /* AC-bit = 1 */
io_store_eflags(eflg);
eflg = io_load_eflags();
if ((eflg & EFLAGS_AC_BIT) != 0) {
/* 如果是386,即使设定AC=1,AC的值还会自动回到0 */
flg486 = 1;
}
eflg &= ~EFLAGS_AC_BIT; /* AC-bit = 0 */
io_store_eflags(eflg);
if (flg486 != 0) {
cr0 = load_cr0();
cr0 |= CR0_CACHE_DISABLE; /* 禁止缓存 */
store_cr0(cr0);
}
i = memtest_sub(start, end);
if (flg486 != 0) {
cr0 = load_cr0();
cr0 &= ~CR0_CACHE_DISABLE; /* 允许缓存 */
store_cr0(cr0);
}
return i;
}
void memman_init(struct MEMMAN *man)
{
man->frees = 0; /* 可用信息数目 */
man->maxfrees = 0; /* 用于观察可用状况:frees的最大值 */
man->lostsize = 0; /* 释放失败的内存的大小总和 */
man->losts = 0; /* 释放失败次数 */
return;
}
unsigned int memman_total(struct MEMMAN *man)
/* 报告空余内存大小的合计 */
{
unsigned int i, t = 0;
for (i = 0; i < man->frees; i++) {
t += man->free[i].size;
}
return t;
}
unsigned int memman_alloc(struct MEMMAN *man, unsigned int size)
/* 分配 */
{
unsigned int i, a;
for (i = 0; i < man->frees; i++) {
if (man->free[i].size >= size) {
/* 找到了足够大的内存 */
a = man->free[i].addr;
man->free[i].addr += size;
man->free[i].size -= size;
if (man->free[i].size == 0) {
/* 如果free[i]变成了0,就减掉一条可用信息 */
man->frees--;
for (; i < man->frees; i++) {
man->free[i] = man->free[i + 1]; /* 代入结构体 */
}
}
return a;
}
}
return 0; /* 没有可用空间 */
}
int memman_free(struct MEMMAN *man, unsigned int addr, unsigned int size)
/* 释放 */
{
int i, j;
/* 为便于归纳内存,将free[]按照addr的顺序排列 */
/* 所以,先决定应该放在哪里 */
for (i = 0; i < man->frees; i++) {
if (man->free[i].addr > addr) {
break;
}
}
/* free[i - 1].addr < addr < free[i].addr */
if (i > 0) {
/* 前面有可用内存 */
if (man->free[i - 1].addr + man->free[i - 1].size == addr) {
/* 可以与前面的可用内存归纳到一起 */
man->free[i - 1].size += size;
if (i < man->frees) {
/* 后面也有 */
if (addr + size == man->free[i].addr) {
/* 也可以与后面的可用内存归纳到一起 */
man->free[i - 1].size += man->free[i].size;
/* man->free[i]删除 */
/* free[i]变成0后归纳到前面去 */
man->frees--;
for (; i < man->frees; i++) {
man->free[i] = man->free[i + 1]; /* 结构体赋值 */
}
}
}
return 0; /* 成功完成 */
}
}
/* 不能与前面的可用空间归纳到一起 */
if (i < man->frees) {
/* 后面还有 */
if (addr + size == man->free[i].addr) {
/* 可以与后面的内容归纳到一起 */
man->free[i].addr = addr;
man->free[i].size += size;
return 0; /* 成功完成 */
}
}
/* 既不能与前面归纳到一起,也不能与后面归纳到一起 */
if (man->frees < MEMMAN_FREES) {
/* free[i]之后的,向后移动,腾出一点可用空间 */
for (j = man->frees; j > i; j--) {
man->free[j] = man->free[j - 1];
}
man->frees++;
if (man->maxfrees < man->frees) {
man->maxfrees = man->frees; /* 更新最大值 */
}
man->free[i].addr = addr;
man->free[i].size = size;
return 0; /* 成功完成 */
}
/* 不能往后移动 */
man->losts++;
man->lostsize += size;
return -1; /* 失败 */
}
unsigned int memman_alloc_4k(struct MEMMAN *man, unsigned int size)
{
unsigned int a;
size = (size + 0xfff) & 0xfffff000;
a = memman_alloc(man, size);
return a;
}
int memman_free_4k(struct MEMMAN *man, unsigned int addr, unsigned int size)
{
int i;
size = (size + 0xfff) & 0xfffff000;
i = memman_free(man, addr, size);
return i;
}