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114 lines
6.3 KiB
114 lines
6.3 KiB
#ifndef _STACK_GENERIC_H
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#define _STACK_GENERIC_H
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#define STACK_STEP 8
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#define STACK_SALT 0xbabb0cac
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// FIXME: find a way to not re-hash the whole stack when removing one item
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// incremental hash for every grow
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#define HASH(p, s, h) \
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{ \
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unsigned char *v = (unsigned char *)(p); \
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for (int x = (s); x; x--) { \
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(h) += v[x-1]; \
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(h) += (h) << 10; \
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(h) ^= (h) >> 6; \
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} \
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(h) += (h) << 3; \
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(h) ^= (h) >> 11; \
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(h) += (h) << 15; \
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}
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// TODO: add a rolling hash
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#define STACK_DECL(stackname, type) \
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struct stackname { \
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type *items; \
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int size, idx, old_idx; \
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unsigned int hash, old_hash; \
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}; \
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\
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\
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struct stackname stackname##_init(void) \
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{ \
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return (struct stackname){0, .hash = STACK_SALT}; \
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} \
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\
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\
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int stackname##_grow(struct stackname *stack, int step) \
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{ \
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if (!stack) \
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return -1; \
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stack->items = realloc(stack->items, (stack->size+step)*sizeof(type)); \
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if(!stack->items) \
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return -1; \
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memset(&(stack->items[stack->size]), 0, step*sizeof(*(stack->items))); \
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stack->size += step; \
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return 0; \
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} \
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\
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\
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int stackname##_push(struct stackname *stack, type *e) \
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{ \
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if (!stack || !e) \
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return -1; \
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if (stack->idx >= stack->size) \
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if (stackname##_grow(stack, STACK_STEP)) \
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return -1; \
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stack->items[stack->idx++] = *e; \
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HASH(e, sizeof(type), stack->hash); \
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return 0; \
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} \
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\
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\
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type stackname##_pop(struct stackname *stack) \
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{ \
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if (!stack || stack->idx == 0 || stack->size == 0) \
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return (type){0}; \
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stack->hash = STACK_SALT; \
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HASH(stack->items, sizeof(type)*(stack->idx-1), stack->hash); \
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return stack->items[stack->idx--]; \
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} \
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\
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\
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int stackname##_clear(struct stackname *stack) \
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{ \
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if (!stack) \
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return -1; \
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stack->old_idx = stack->idx; \
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stack->old_hash = stack->hash; \
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stack->hash = STACK_SALT; \
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stack->idx = 0; \
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return 0; \
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} \
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\
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\
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int stackname##_changed(struct stackname *stack) \
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{ \
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if (!stack) \
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return -1; \
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return stack->hash != stack->old_hash; \
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} \
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\
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\
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int stackname##_size_changed(struct stackname *stack) \
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{ \
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if (!stack) \
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return -1; \
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return stack->size != stack->old_idx; \
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} \
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\
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\
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int stackname##_free(struct stackname *stack) \
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{ \
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if (stack) { \
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stackname##_clear(stack); \
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if (stack->items) \
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free(stack->items); \
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} \
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return 0; \
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} \
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#endif
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