/* * (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands. * See the copyright notice in the ACK home directory, in the file "Copyright". */ #include "param.h" #include "impl.h" #include "check.h" #include "phys.h" /* Physical manipulations. The blocks concerned are not in any logical chain. */ public mallink * create_chunk(p, n) char *p; unsigned int n; { /* The newly acquired piece of memory at p, of length n, is turned into a free chunk, properly chained in the physical chain. The address of the chunk is returned. */ register mallink *ml; /* All of malloc memory is followed by a virtual chunk, the mallink of which starts mallink_size() bytes past the last byte in memory. Its use is prevented by testing for ml == ml_last first. */ register mallink *last = ml_last; assert(!last || p == (char *)phys_next_of(last) - mallink_size()); ml = (mallink *)(p + mallink_size()); /* bump ml */ started_working_on(ml); set_free(ml, 1); set_phys_prev(ml, last); ml_last = ml; set_phys_next(ml, (mallink *)((char *)ml + n)); calc_checksum(ml); assert(size_of(ml) + mallink_size() == n); if (last && free_of(last)) { coalesce_backw(ml, last); ml = last; } check_mallinks("create_chunk, phys. linked"); return ml; } public truncate(ml, size) register mallink *ml; unsigned int size; { /* The chunk ml is truncated. The chunk at ml is split in two. The remaining part is then freed. */ register mallink *new = (mallink *)((char *)ml + size); register mallink *ph_next = phys_next_of(ml); set_free(new, 1); set_phys_prev(new, ml); set_phys_next(new, ph_next); calc_checksum(new); if (! last_mallink(ml)) { set_phys_prev(ph_next, new); calc_checksum(ph_next); if (free_of(ph_next)) coalesce_forw(new, ph_next); } else ml_last = new; set_phys_next(ml, new); calc_checksum(ml); started_working_on(new); link_free_chunk(new); stopped_working_on(new); check_mallinks("truncate"); } public combine_chunks(ml1, ml2) register mallink *ml1, *ml2; { /* The chunks ml1 and ml2 are combined. */ register mallink *ml3 = phys_next_of(ml2); set_phys_next(ml1, ml3); calc_checksum(ml1); if (!last_mallink(ml2)) { set_phys_prev(ml3, ml1); calc_checksum(ml3); } if (ml_last == ml2) ml_last = ml1; }