102 lines
2.1 KiB
NASM
102 lines
2.1 KiB
NASM
%ifndef __INC_ARENA_ALLOC_FUNC
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%define __ARENA_HEAP_START 0x8000
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%define __ARENA_HEAP_SIZE 0x6000 ; 0x8000 -> 0xE000 = 24KiB of Heap
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struc ArenaStateStruc_t
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.start resw 1
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.end resw 1
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.mark resw 1
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endstruc
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; void arena_init(ArenaState *a)
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;
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arena_init:
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__CDECL16_ENTRY
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.func:
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movzx eax, word [bp + 4] ; ptr to state structure
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mov di, ax
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xor eax, eax
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mov word [di + ArenaStateStruc_t.mark], eax
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mov word [di + ArenaStateStruc_t.end], word (__ARENA_HEAP_START + __ARENA_HEAP_SIZE)
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mov word [di + ArenaStateStruc_t.start], __ARENA_HEAP_START
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; zero out heap area on init
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; void* kmemset_byte(void* dst, uint8_t val, uint16_t len);
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mov ax, __ARENA_HEAP_SIZE
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push ax ; len
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xor ax, ax
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push ax ; val = 0
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mov ax, __ARENA_HEAP_START
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push ax ; dst
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call kmemset
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add sp, 0x6
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.endp:
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__CDECL16_EXIT
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ret
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; size_t align_up(size_t x, size_t a)
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; eax, ebx. ecx are all clobbered
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arena_align_up:
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__CDECL16_ENTRY
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.func:
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; align x up to the nearest specified alignment (a)
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; (x + (a-1)) & ~(a-1)
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mov eax, [bp + 4] ; x
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mov ebx, [bp + 6] ; a - 1
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sub ebx, 1
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mov ecx, eax
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add ecx, ebx ; x + (a+1)
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not ebx
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and ecx, ebx ; ecx contains the result
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xor eax, eax
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xor ebx, ebx
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mov eax, ecx ; return result in eax
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xor ecx, ecx
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.endp:
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__CDECL16_EXIT
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ret
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; void* arena_alloc(void* a, size_t bytes, size_t align)
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arena_alloc:
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__CDECL16_ENTRY
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.func:
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; remove bytes from pool and increment mark to the new cursor location
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; return a pointer to the begining of allocated segment
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.endp:
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__CDECL16_EXIT
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ret
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arena_mark:
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__CDECL16_ENTRY
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.func:
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; return the current location of the 'cursor' in the allocator
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.endp:
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__CDECL16_EXIT
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ret
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arena_reset_to:
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__CDECL16_ENTRY
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.func:
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; rewind the arena to a previously marked point
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.endp:
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__CDECL16_EXIT
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ret
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arena_reset:
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__CDECL16_ENTRY
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.func:
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; reset the entire heap to a fresh state
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.endp:
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__CDECL16_EXIT
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ret
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%endif
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%define __INC_ARENA_ALLOC_FUNC |