advent-of-code

am_memory.h (4817B)

---

 #ifndef AM_MEMORY_H
 #define AM_MEMORY_H
 
 #define MEM_KIB(b) ((u64)(b) << 10)
 #define MEM_MIB(b) ((u64)(b) << 20)
 #define MEM_GIB(b) ((u64)(b) << 30)
 
 #define AM_MEM_RESERVE_FN(name) void *(name)(void *ctx, u64 size)
 typedef AM_MEM_RESERVE_FN(am_mem_reserve_fn);
 
 #define AM_MEM_CHANGE_FN(name) void (name)(void *ctx, void *ptr, u64 size)
 typedef AM_MEM_CHANGE_FN(am_mem_change_fn);
 
 typedef struct {
     am_mem_reserve_fn* reserve;
     am_mem_change_fn* commit;
     am_mem_change_fn* decommit;
     am_mem_change_fn* release;
     void *ctx;
 } BaseAllocator;
 
 #define AM_MEM_ARENA_COMMIT_BLOCK_SIZE MEM_MIB(64)
 #define AM_MEM_ARENA_DEFAULT_RESERVE_SIZE MEM_GIB(1)
 
 typedef struct {
     BaseAllocator *base;
     u8 *mem;
     u64 cap;
     u64 pos;
     u64 commit_pos;
 } MemArena;
 
 internal AM_MEM_CHANGE_FN(am_mem_change_noop) {
     UNUSED(ctx);
     UNUSED(ptr);
     UNUSED(size);
 }
 
 internal AM_MEM_RESERVE_FN(am_mem_reserve_malloc) {
     UNUSED(ctx);
     return malloc(size);
 }
 
 internal AM_MEM_CHANGE_FN(am_mem_release_malloc) {
     UNUSED(ctx);
     UNUSED(size);
     free(ptr);
 }
 
 internal BaseAllocator *am_mem_base_allocator_malloc(void) {
     local_persist BaseAllocator b;
     if (!b.reserve) {
         b = (BaseAllocator) {
             .reserve = am_mem_reserve_malloc,
             .commit = am_mem_change_noop,
             .decommit = am_mem_change_noop,
             .release = am_mem_release_malloc,
         };
     }
     return &b;
 }
 
 internal MemArena am_mem_arena_create_reserve(BaseAllocator *base, u64 reserve_size) {
     MemArena a = {
         .base = base,
     };
     a.mem = a.base->reserve(a.base->ctx, reserve_size);
     a.cap = reserve_size;
     return a;
 }
 
 internal MemArena am_mem_arena_create(BaseAllocator *base) {
     return am_mem_arena_create_reserve(base, AM_MEM_ARENA_DEFAULT_RESERVE_SIZE);
 }
 
 internal void *am_mem_arena_push(MemArena *a, u64 size) {
     void *result = NULL;
     if (a->mem + size <= a->mem + a->cap) {
         result = a->mem + a->pos;
         a->pos += size;
 
         if (a->pos > a->commit_pos) {
             u64 aligned = ALIGN_UP_POW_2(a->pos, AM_MEM_ARENA_COMMIT_BLOCK_SIZE);
             u64 next_commit_pos = CLAMP_TOP(aligned, a->cap);
             u64 commit_size = next_commit_pos - a->commit_pos;
             a->base->commit(a->base->ctx, a->mem + a->commit_pos, commit_size);
             a->commit_pos = next_commit_pos;
         }
     }
     return result;
 }
 
 #define AM_MEM_ARENA_PUSH_ARRAY(arena, T, count) (am_mem_arena_push((arena), sizeof(T) * (count)))
 
 internal void am_mem_arena_pop_to(MemArena *a, u64 pos) {
     if (pos < a->pos) {
         a->pos = pos;
 
         u64 aligned = ALIGN_UP_POW_2(a->pos, AM_MEM_ARENA_COMMIT_BLOCK_SIZE);
         u64 next_commit_pos = CLAMP_TOP(aligned, a->cap);
         if (next_commit_pos < a->commit_pos) {
             u64 decommit_size = a->commit_pos - next_commit_pos;
             a->base->decommit(a->base->ctx, a->mem + a->commit_pos, decommit_size);
             a->commit_pos = next_commit_pos;
         }
     }
 }
 
 internal void am_mem_arena_release(MemArena *a) {
     a->base->release(a->base->ctx, a->mem, a->cap);
     *a = (MemArena){0};
 }
 
 // TODO: SIMD
 internal void am_mem_copy(void *dst, void *src, u64 size) {
     for (u64 i = 0; i < size; i++) {
         ((u8 *)dst)[i] = ((u8 *)src)[i];
     }
 }
 
 internal bool am_mem_equal(void *dst, void *src, u64 size) {
     for (u64 i = 0; i < size; i++) {
         if (((u8 *)dst)[i] != ((u8 *)src)[i]) {
             return false;
         }
     }
     return true;
 }
 
 #if defined(AM_INCLUDE_TESTS)
 internal void am_memory_test(void) {
     assert(MEM_KIB(10) == 10240);
     assert(MEM_MIB(10) == 10485760);
     assert(MEM_GIB(10) == 10737418240);
 
     {
         BaseAllocator *a = am_mem_base_allocator_malloc();
         u64 num_test_ints = 10;
         s32 *int_buf = a->reserve(NULL, num_test_ints * sizeof(s32));
         assert(int_buf);
         a->release(NULL, int_buf, 0);
     }
 
     {
         MemArena a = am_mem_arena_create(am_mem_base_allocator_malloc());
         am_mem_arena_push(&a, 1020);
         assert(a.pos == 1020);
         u64 p = a.pos;
         u64 cp = a.commit_pos;
 
         AM_MEM_ARENA_PUSH_ARRAY(&a, u8, a.cap - a.pos);
         assert(a.pos == a.cap);
         assert(a.commit_pos == a.cap);
 
         am_mem_arena_pop_to(&a, p);
         assert(a.pos == p);
         assert(a.commit_pos == cp);
 
         am_mem_arena_release(&a);
         assert(a.pos == 0);
         assert(a.commit_pos == 0);
         assert(a.mem == NULL);
     }
 
     {
         u8 src[10] = {0};
         u8 dst[10] = {0};
         for (u64 i = 0; i < ARRAY_COUNT(src); i++) {
             src[i] = i;
         }
 
         am_mem_copy(dst, src, ARRAY_COUNT(dst));
         assert(am_mem_equal(dst, src, ARRAY_COUNT(dst)));
     }
 }
 #endif // defined(AM_INCLUDE_TESTS)
 
 #endif // AM_MEMORY_H