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#if defined(__linux__)
#define _DEFAULT_SOURCE
#endif
#include "common.h"
#include "smrt_arena.h"
#include <string.h>
smrt_arena_t *smrt_arena_create(u64 reserve_size, u64 commit_size, b32 auto_decommit) {
u32 pagesize = plat_get_pagesize();
reserve_size = ALIGN_UP_POW2(reserve_size + sizeof(smrt_arena_t), pagesize);
commit_size = ALIGN_UP_POW2( commit_size, pagesize);
smrt_arena_t *arena = plat_mem_reserve(reserve_size);
if (!plat_mem_commit(arena, commit_size)) {
return NULL;
}
arena->reserve_size = reserve_size;
arena->commit_size = commit_size;
arena->commit_pos = commit_size;
arena->pos = SMRT_ARENA_BASE_POS;
arena->mark_pos = 0;
arena->auto_decommit = auto_decommit;
return arena;
}
static void smrt_arena__shrink_commit(smrt_arena_t *arena) {
if (!arena->auto_decommit) { return; }
u64 target_commit_pos = arena->pos + arena->commit_size - 1;
target_commit_pos -= target_commit_pos % arena->commit_size;
if (target_commit_pos >= arena->commit_pos) { return; }
u64 decommit_size = arena->commit_pos - target_commit_pos;
u8 *decommit_start = (u8*)arena + target_commit_pos;
if (plat_mem_decommit(decommit_start, decommit_size)) {
arena->commit_pos = target_commit_pos;
if (arena->mark_pos > arena->commit_pos) {
arena->mark_pos = 0;
}
}
}
void *smrt_arena_push(smrt_arena_t *arena, u64 alloc_amount, b32 zero_out) {
u64 pos_aligned = ALIGN_UP_POW2(arena->pos, ARENA_ALIGN);
u64 new_pos = pos_aligned + alloc_amount;
if (new_pos > arena->reserve_size) { return NULL; }
if (new_pos > arena->commit_pos) {
u64 new_commit_pos = new_pos;
new_commit_pos += arena->commit_size - 1;
new_commit_pos -= new_commit_pos % arena->commit_size;
new_commit_pos = MIN(new_commit_pos, arena->reserve_size);
u8 *mem = (u8*)arena + arena->commit_pos;
u64 commit_size = new_commit_pos - arena->commit_pos;
if (!plat_mem_commit(mem, commit_size)) {
return NULL;
}
arena->commit_pos = new_commit_pos;
}
arena->pos = new_pos;
u8 *out = (u8*)arena + pos_aligned;
if (zero_out) {
memset(out, 0, alloc_amount);
}
return out;
}
void *smrt_arena_mark_push(smrt_arena_t *arena, u64 alloc_amount, b32 zero_out) {
u64 orig_pos = arena->pos;
void *mem = smrt_arena_push(arena, alloc_amount, zero_out);
if (mem) {
arena->mark_pos = orig_pos;
}
return mem;
}
void smrt_arena_pop(smrt_arena_t *arena, u64 pop_amount) {
pop_amount = MIN(pop_amount, arena->pos - SMRT_ARENA_BASE_POS);
arena->pos -= pop_amount;
smrt_arena__shrink_commit(arena);
}
void smrt_arena_pop_to(smrt_arena_t *arena, u64 pos) {
u64 size = pos < arena->pos ? arena->pos - pos : 0;
smrt_arena_pop(arena, size);
}
b32 smrt_arena_pop_to_mark(smrt_arena_t *arena) {
if (arena->mark_pos == 0) {
return false;
}
smrt_arena_pop_to(arena, arena->mark_pos);
return true;
}
void smrt_arena_clear(smrt_arena_t *arena, b32 zero_out) {
arena->pos = SMRT_ARENA_BASE_POS;
if (zero_out) {
memset((u8*)arena + SMRT_ARENA_BASE_POS, 0, arena->commit_size - SMRT_ARENA_BASE_POS);
}
smrt_arena__shrink_commit(arena);
}
void smrt_arena_destroy(smrt_arena_t *arena) {
plat_mem_release(arena, arena->reserve_size);
}
#if defined(_WIN32)
#include <windows.h>
u32 plat_get_pagesize(void) {
SYSTEM_INFO sysinfo = { 0 };
GetSystemInfo(&sysinfo);
return sysinfo.dwPageSize;
}
void* plat_mem_reserve(u64 size) {
return VirtualAlloc(NULL, size, MEM_RESERVE, PAGE_READWRITE);
}
b32 plat_mem_commit(void* ptr, u64 size) {
void* ret = VirtualAlloc(ptr, size, MEM_COMMIT, PAGE_READWRITE);
return ret != NULL;
}
b32 plat_mem_decommit(void* ptr, u64 size) {
return VirtualFree(ptr, size, MEM_DECOMMIT);
}
b32 plat_mem_release(void* ptr, u64 size) {
return VirtualFree(ptr, size, MEM_RELEASE);
}
#elif defined(__linux__)
#include <unistd.h>
#include <sys/mman.h>
u32 plat_get_pagesize(void) {
return (u32)sysconf(_SC_PAGESIZE);
}
void* plat_mem_reserve(u64 size) {
void* out = mmap(NULL, size, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (out == MAP_FAILED) {
return NULL;
}
return out;
}
b32 plat_mem_commit(void* ptr, u64 size) {
i32 ret = mprotect(ptr, size, PROT_READ | PROT_WRITE);
return ret == 0;
}
b32 plat_mem_decommit(void* ptr, u64 size) {
i32 ret = mprotect(ptr, size, PROT_NONE);
if (ret != 0) return false;
ret = madvise(ptr, size, MADV_DONTNEED);
return ret == 0;
}
b32 plat_mem_release(void* ptr, u64 size) {
i32 ret = munmap(ptr, size);
return ret == 0;
}
#endif
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