Imbus/xv6-riscv-kernel
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rearrangements and cleanup for text

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This commit is contained in:
Russ Cox 2009-07-11 19:26:01 -07:00
parent 2de1c550ca
commit f9a06440ab
4 changed files with 102 additions and 107 deletions
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40
kalloc.c
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@ -22,21 +22,20 @@ struct {
// Initialize free list of physical pages.
// This code cheats by just considering one megabyte of
// pages after _end. Real systems would determine the
// pages after end. Real systems would determine the
// amount of memory available in the system and use it all.
void
kinit(void)
{
extern int end;
uint mem;
char *start;
extern char end[];
uint len;
char *p;
initlock(&kmem.lock, "kmem");
start = (char*) &end;
start = (char*) (((uint)start + PAGE) & ~(PAGE-1));
mem = 256; // assume computer has 256 pages of RAM
cprintf("mem = %d\n", mem * PAGE);
kfree(start, mem * PAGE);
p = (char*)(((uint)end + PAGE) & ~(PAGE-1));
len = 256*PAGE; // assume computer has 256 pages of RAM, 1 MB
cprintf("mem = %d\n", len);
kfree(p, len);
}
// Free the len bytes of memory pointed at by v,
@ -61,13 +60,7 @@ kfree(char *v, int len)
rend = (struct run*)((char*)r + r->len);
if(r <= p && p < rend)
panic("freeing free page");
if(pend == r){ // p next to r: replace r with p
p->len = len + r->len;
p->next = r->next;
*rp = p;
goto out;
}
if(rend == p){ // r next to p: replace p with r
if(rend == p){ // r before p: expand r to include p
r->len += len;
if(r->next && r->next == pend){ // r now next to r->next?
r->len += r->next->len;
@ -75,6 +68,12 @@ kfree(char *v, int len)
}
goto out;
}
if(pend == r){ // p before r: expand p to include, replace r
p->len = len + r->len;
p->next = r->next;
*rp = p;
goto out;
}
}
// Insert p before r in list.
p->len = len;
@ -99,14 +98,11 @@ kalloc(int n)
acquire(&kmem.lock);
for(rp=&kmem.freelist; (r=*rp) != 0; rp=&r->next){
if(r->len == n){
*rp = r->next;
release(&kmem.lock);
return (char*)r;
}
if(r->len > n){
if(r->len >= n){
r->len -= n;
p = (char*)r + r->len;
if(r->len == 0)
*rp = r->next;
release(&kmem.lock);
return p;
}