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physmem.c: improved correctness and efficiency of alignment

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- physmem.c (align_brk): don't waste memory if already aligned
- physmem.c (ALIGN, calloc_phys_vec): align by DMA transfer size
- physmem.c (calloc_phys_vec): make sure allocations don't straddle
  page boundaries
- physmem.c (xlat_one): print "unsigned long" with %lx, not %x
This commit is contained in:
Werner Almesberger 2011-05-02 04:43:18 -03:00
parent 893884c91f
commit 0dbf29e599
1 changed files with 12 additions and 4 deletions
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16
ubb-vga/physmem.c
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@ -28,19 +28,24 @@
#define PM_SWAPPED 62 #define PM_SWAPPED 62
#define PM_PRESENT 63 #define PM_PRESENT 63
#define ALIGN 32 /* DMA transfer size */
static void align_brk(int alignment) static void align_brk(int alignment)
{ {
unsigned long addr; unsigned long addr, remainder;
addr = (unsigned long) sbrk(0); addr = (unsigned long) sbrk(0);
sbrk(alignment-(addr % alignment)); remainder = addr % alignment;
if (remainder)
sbrk(alignment-remainder);
} }
void **calloc_phys_vec(size_t n, size_t size) void **calloc_phys_vec(size_t n, size_t size)
{ {
void **vec; void **vec;
unsigned long pos;
int i; int i;
vec = malloc(sizeof(void *)*n); vec = malloc(sizeof(void *)*n);
@ -50,7 +55,10 @@ void **calloc_phys_vec(size_t n, size_t size)
} }
for (i = 0; i != n; i++) { for (i = 0; i != n; i++) {
align_brk(512); /* crude page alignment */ align_brk(ALIGN);
pos = (unsigned long) sbrk(0);
if ((pos & ~(PAGE_SIZE-1)) != ((pos+size) & ~(PAGE_SIZE-1)))
sbrk(PAGE_SIZE-(pos & (PAGE_SIZE-1)));
vec[i] = sbrk(size); vec[i] = sbrk(size);
memset(vec[i], 0, size); memset(vec[i], 0, size);
} }
@ -94,7 +102,7 @@ static unsigned long xlat_one(int fd, unsigned long vaddr)
abort(); abort();
} }
paddr = ((map & 0x7fffffffffffffULL) << pshift) | offset; paddr = ((map & 0x7fffffffffffffULL) << pshift) | offset;
// fprintf(stderr, "0x%x -> 0x%x\n", vaddr, paddr); // fprintf(stderr, "0x%lx -> 0x%lx\n", vaddr, paddr);
return paddr; return paddr;
} }