88 lines
No EOL
2.7 KiB
C
88 lines
No EOL
2.7 KiB
C
/*
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Copyright 2019 Benji Dial
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Permission to use, copy, modify, and/or distribute this
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software for any purpose with or without fee is hereby
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granted, provided that the above copyright notice and this
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permission notice appear in all copies.
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THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS
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ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO
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EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
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INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
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RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
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ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
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OF THIS SOFTWARE.
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*/
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#include "mem.h"
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uint32_t last_byte = 0;
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uint32_t last_mask = 0x00000001;
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void *allocate_block(uint32_t size, uint16_t proc_n) {
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for (struct mmap_entry *find = mmap_start; find; find = find->after)
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if (!find->whose) {
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if (find->length == size) {
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find->whose = proc_n;
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return (void *)find->base;
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}
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else if (find->length > size) {
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uint32_t byte = last_byte;
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uint32_t mask = last_mask;
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while (mmap_bitmap[byte] & mask) {
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if ((byte == last_byte) && (mask == last_mask)) {
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while (find = find->after)
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if (find->length == size) {
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find->whose = proc_n;
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return (void *)find->base;
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}
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return (void *)0;
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}
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if (!(mask <<= 1)) {
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mask = 0x00000001;
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if (++byte == MMAP_SIZE)
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byte = 0;
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}
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}
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mmap_bitmap[last_byte = byte] |= last_mask = mask;
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struct mmap_entry *new = mmap_bss + (byte << 5);
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while (mask >>= 1)
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++new;
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((((new->after = find->after)->before = new)->before = find)->after = new)->base = find->base + size;
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new->length = find->length - size;
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find->length = size;
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find->whose = proc_n;
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new->whose = FREE;
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return (void *)find->base;
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}
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}
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return (void *)0;
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}
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void deallocate_block(void *start) {
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struct mmap_entry *find = mmap_start;
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while (find->base != (uint32_t)start)
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if (find->after)
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find = find->after;
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else
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return;
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find->whose = FREE;
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while (find->before && !find->before->whose) {
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find->before->length += find->length;
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if (find->before->after = find->after)
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find->after->before = find->before;
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unmark_entry(find);
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find = find->before;
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}
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if (!find->before)
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mmap_start = find;
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while (find->after && !find->after->whose) {
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find->length += find->after->length;
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unmark_entry(find->after);
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if (find->after = find->after->after)
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find->after->before = find;
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}
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} |