so I added free, no idea if it works because I need to start hw 💀
This commit is contained in:
Bryan McShea
@@ -12,7 +12,7 @@
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# block node
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.equ bsize, 0
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.equ binfo, 0
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.equ fb_next, 8 # free only
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# free also contains its address at the end
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@@ -37,7 +37,8 @@ heap_oom:
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.align 4
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.global heap_info # global for testing only
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.equ heap_last_used, 0 # last free block will set this
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.equ heap_last_used, 0 # is the last block used;
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# matches binfo
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.equ heap_first_free, 8 # matches fb_next
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.equ heap_start, 16
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.equ heap_end, 24
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@@ -88,7 +89,7 @@ heap_init:
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# create initial free block
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ori t2, t2, prev_used # add prev used
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sd t2, bsize(t1) # store size
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sd t2, binfo(t1) # store size
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sd t0, fb_next(t1) # store next
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sd t1, -8(a0) # store addr at end
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@@ -115,8 +116,9 @@ heap_alloc:
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addi t0, t0, align_imask
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andi t0, t0, align_mask
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# step 1:
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# get a free block that will fit (t1)
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# and its free space
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# and its free space (t2)
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la t3, heap_info
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ld t4, heap_first_free(t3)
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@@ -131,8 +133,10 @@ heap_alloc:
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move t1, t4 # current block (t1)
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# loop through free blocks
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0:
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ld t2, bsize(t1) # size of current block (t2)
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ld t2, binfo(t1) # size of current block (t2)
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andi t2, t2, size_mask
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bgeu t2, t0, 0f # is it big enough
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ld t5, fb_next(t1) # if not, get the next
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@@ -140,7 +144,9 @@ heap_alloc:
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move t6, t1
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move t1, t5
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j 0b
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1: # if no blocks are big enough
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add t5, t1, t2 # get end of last free block
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beq t5, a1, 2f # if no free block at end of heap:
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move t6, t1
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@@ -152,10 +158,11 @@ heap_alloc:
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sd a0, heap_end(t3) # update end in info
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sub t2, a0, t1 # new free space (t2)
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andi t5, t2, prev_used # prev used bit
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sd t5, bsize(t1) # update size
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sd t5, binfo(t1) # update size
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sd t3, fb_next(t1) # update next (for case 3)
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0:
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# step 2:
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# deal with extra free space
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sub t5, t2, t0 # unneeded free space (t5)
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@@ -167,27 +174,30 @@ heap_alloc:
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add t6, t3, t5 # store addr at end
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sd t3, -8(t6)
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ori t6, t5, prev_used # store size with prev in use
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sd t6, bsize(t3)
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sd t6, binfo(t3)
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ld t6, fb_next(t1) # copy next
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sd t6, fb_next(t3)
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move t5, t3
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j 1f
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0:
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move t0, t2 # if no space, fill in with used
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0: # if no space, fill in with used
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move t0, t2
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ld t4, fb_next(t1)
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sd t4, fb_next(t6) # set prev next to cur next
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ld t4, heap_end(t3)
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add t3, t1, t0
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beq t3, t4, 1f # if this is not at the end
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ld t4, bsize(t3) # set next's prev used to 1
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add t5, t1, t0
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bne t5, t4, 1f # if this is at the end
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move t5, t3 # select the heap info for next
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1: # either way
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ld t4, binfo(t5) # set next's prev used to 1
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ori t4, t4, prev_used
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sd t4, bsize(t3)
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1:
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sd t4, binfo(t5)
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# step 3:
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# create used block
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add t2, t0, t1 # end of block
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ori t0, t0, prev_used # prev used bit
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sd t0, bsize(t1) # store size
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sd t0, binfo(t1) # store size
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sd zero, fb_next(t1) # remove free block stuff
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sd zero, -8(t2)
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@@ -202,6 +212,53 @@ heap_alloc:
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# a0 - address
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.global heap_free
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heap_free:
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ld t2, binfo(a0)
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andi t0, t2, size_mask # t0 = size
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la t3, heap_info # t3 = heap info
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sd t4, heap_end(t3) # t4 = heap end
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# step 1:
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# merge with prev if possible
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andi t1, t2, prev_used # t1 = prev used
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bnez t1, 0f # if prev not used:
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ld a0, -8(a0) # a0 = prev block addr
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ld t2, binfo(a0)
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andi t1, t2, size_mask # t1 = prev size
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add t0, t0, t1 # add to size
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0:
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# step 2:
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# merge with next if possible
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add t2, a0, t0 # t2 = next block
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bge t2, t4, 0f # skip if end
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ld t1, binfo(t2)
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andi t1, t1, size_mask # t1 = next size
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add t2, t2, t1 # t2 = next next block
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blt t2, t4, 1f # if end:
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ld t2, binfo(t3) # t2 = last block is used
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bnez t2, 0f # skip if used
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j 2f # if end free, we can use
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1: # if not end:
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ld t2, binfo(t2)
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andi t2, t2, prev_used # t2 = next used (n->n->pu)
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bnez t2, 0f # if next not used:
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2: # as long as not skipped:
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add t0, t0, t1 # add to size
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0:
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# step 3:
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# write block
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ori t1, t0, prev_used # set prev used
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sd t1, binfo(a0) # store info
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ld t2, fb_next(t3) # insert at head of free list
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sd t2, fb_next(a0)
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sd a0, fb_next(t3)
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add t1, a0, t0 # get next addr
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sd a0, -8(t1) # store addr at end
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ret
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# args:
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@@ -39,6 +39,10 @@ heap_test:
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# put stuff on heap
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li a0, 8*9
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jal heap_alloc
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li a0, 8*4
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jal heap_alloc
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li t0, 0x1111111111111111
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