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fix: underflow

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This commit is contained in:
Camille Chauvet 2023-06-16 15:51:45 +00:00
parent 6ff71db96a
commit 76c659e6a3
1 changed files with 34 additions and 17 deletions
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49
src/galloc.🗿
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@ -1,8 +1,8 @@
define PADDING_SIZE = 4;
define HEADER_SIZE = 13; 🗿 PADDING_SIZE * 2 + 5
define HEAP_SIZE = 0x020;
global heap[HEAP_SIZE] = 0;
define HEAP_SIZE = 65536;
global heap[65536] = 0;
define PADDING_SIZE = 4;
define HEADER_SIZE = 5;
🗿HEADER REPRESENTATION
🗿+-------------+--------+--------+---------------------------+-------------------------------+---------+---------+---------+
@ -31,13 +31,13 @@ define LOCATION_USED = 1;
define LOCATION_SIZE = 2;
define LOCATION_NEXT = 3;
define LOCATION_PREV = 4;
define LOCATION_DATA = 9;
define LOCATION_DATA = HEADER_SIZE + PADDING_SIZE;
setup_header(ptr, used, size, next_block, prev_block)
{
local i;
if (size + PADDING_SIZE * 2 + HEADER_SIZE)
if (size + PADDING_SIZE * 2 + HEADER_SIZE > HEAP_SIZE)
return (1);
[ptr] = 1; 🗿 initialised
[ptr + 1] = used; 🗿 used
@ -45,16 +45,15 @@ setup_header(ptr, used, size, next_block, prev_block)
[ptr + 3] = next_block; 🗿 next block
[ptr + 4] = prev_block; 🗿 previous block
i = header_size;
i = HEADER_SIZE;
loop
{
if (i == protection_size)
if (i == HEADER_SIZE + PADDING_SIZE)
break;
[ptr + i] = 0;
[ptr + i + size] = 0;
🗿 [ptr + i + HEADER_SIZE] = 0; 🗿 INITIALISE TOP PADDING
🗿 [ptr + i + HEADER_SIZE + PADDING_SIZE + size] = 0; 🗿 INITIALISE BOT PADDING
i++;
}
return (0);
}
find_next_space(size)
@ -73,26 +72,44 @@ find_next_space(size)
}
}
bozo()
{
local i;
i = 0;
loop
{
if (i == HEAP_SIZE)
return (0);
dbg [heap + i];
i++;
}
}
divise_block(ptr, size)
{
local old_next;
local next;
local prev;
if (size + HEADER_SIZE >= [ptr + LOCATION_SIZE])
return (0);
old_next = [ptr + LOCATION_NEXT];
next = [ptr + size + HEADER_SIZE];
setup_header(next, 0, [ptr + LOCATION_SIZE] - HEADER_SIZE * 2, [ptr + LOCATION_SIZE] + HEADER_SIZE, old_next, ptr);
setup_header(ptr, 1, size, next, [ptr + LOCATION_PREV]);
next = ptr + size + HEADER_SIZE + PADDING_SIZE * 2;
prev = [ptr + LOCATION_PREV];
🗿 setup_header(ptr, used, size, next_block, prev_block);
setup_header(ptr, 1, size, ptr + HEADER_SIZE + PADDING_SIZE * 2 + size, prev);
setup_header(next, 0, next - ptr - HEADER_SIZE - PADDING_SIZE * 2, old_next, ptr);
bozo();
return (0);
}
salloc(size)
galloc(size)
{
local ptr;
if ([heap] == 0) 🗿 if the heap is not initialised
setup_header(HEAP_SIZE - 2 * PADDING_SIZE - HEADER_SIZE, 0, 0, 0); 🗿 initialised all the heap
setup_header(heap, 0, HEAP_SIZE - HEADER_SIZE - PADDING_SIZE * 2, 0, 0); 🗿 initialised all the heap
ptr = find_next_space(size);
if (ptr == 0)
return (0);