Scratch and temp arenas

2 files changed, 69 insertions, 3 deletions

diff --git a/src/smrt_arena.c b/src/smrt_arena.c
index 0fb8ab7..6862212 100644
--- a/src/smrt_arena.c
+++ b/src/smrt_arena.c
@@ -7,6 +7,9 @@
 
 #include <string.h>
 
+
+static __thread smrt_arena_t *_scratch_pool[SCRATCH_POOL_SIZE] = { 0 };
+
 smrt_arena_t *smrt_arena_create(u64 reserve_size, u64 commit_size, b32 auto_decommit) {
     u32 pagesize = plat_get_pagesize();
 
@@ -135,6 +138,52 @@ void smrt_arena_destroy(smrt_arena_t *arena) {
     plat_mem_release(arena, arena->reserve_size);
 }
 
+smrta_temp_t smrta_temp_start(smrt_arena_t *arena) {
+    return (smrta_temp_t){
+            .arena=arena,
+        .start_pos=arena->pos
+    };
+}
+
+void smrta_temp_end(smrta_temp_t temp) {
+    smrt_arena_pop_to(temp.arena, temp.start_pos);
+}
+
+smrta_temp_t smrta_scratch_start(smrt_arena_t **conflicts, u32 num_conflicts) {
+    i32 candidate_idx = -1;
+
+    for (i32 i = 0; i < SCRATCH_POOL_SIZE; i++) {
+        b32 conflict_found = false;
+
+        for (u32 j = 0; j < num_conflicts; j++) {
+            if (_scratch_pool[i] == conflicts[j]) {
+                conflict_found = true;
+            }
+        }
+
+        if (!conflict_found) {
+            candidate_idx = i;
+            break;
+        }
+    }
+
+    if (candidate_idx != -1) {
+        smrt_arena_t **selected = &_scratch_pool[candidate_idx];
+
+        if (!*selected) {
+            *selected = smrt_arena_create(MiB(64), plat_get_pagesize(), true);
+        }
+
+        return smrta_temp_start(*selected);
+    }
+
+    return (smrta_temp_t){ 0 };
+}
+
+void smrta_scratch_end(smrta_temp_t scratch) {
+    smrta_temp_end(scratch);
+}
+
 #if defined(_WIN32)
 
 #include <windows.h>
diff --git a/src/smrt_arena.h b/src/smrt_arena.h
index 375929d..0c8d848 100644
--- a/src/smrt_arena.h
+++ b/src/smrt_arena.h
@@ -18,16 +18,33 @@ typedef struct {
 
 smrt_arena_t     *smrt_arena_create(u64 reserve_size, u64 commit_size, b32 auto_decommit);
         void       *smrt_arena_push(smrt_arena_t *arena, u64 alloc_amount, b32 zero_out);
-        void  *smrt_arena_mark_push(smrt_arena_t *arena, u64 alloc_amount, b32 zero_out);
         void         smrt_arena_pop(smrt_arena_t *arena, u64 pop_amount);
         void      smrt_arena_pop_to(smrt_arena_t *arena, u64 location);
-         b32 smrt_arena_pop_to_mark(smrt_arena_t *arena);
         void       smrt_arena_clear(smrt_arena_t *arena, b32 zero_out);
-        void        smrt_arena_mark(smrt_arena_t *arena);
         void     smrt_arena_destroy(smrt_arena_t *arena);
 
+        void        smrt_arena_mark(smrt_arena_t *arena);
+        void  *smrt_arena_mark_push(smrt_arena_t *arena, u64 alloc_amount, b32 zero_out);
+         b32 smrt_arena_pop_to_mark(smrt_arena_t *arena);
+
 #define SMRTA_ALLOC_ARRAY(arena, T, n) (T*)smrt_arena_push(arena, sizeof(T) * (n), true)
 
+typedef struct {
+    smrt_arena_t *arena;
+            u64   start_pos;
+} smrta_temp_t;
+
+smrta_temp_t smrta_temp_start(smrt_arena_t *arena);
+        void   smrta_temp_end(smrta_temp_t temp);
+
+smrta_temp_t smrta_scratch_start(smrt_arena_t **conflicts, u32 num_conflicts);
+        void   smrta_scratch_end(smrta_temp_t temp);
+
+#define SCRATCH_POOL_SIZE 2
+
+#define TEMP_ARENA_PUSH(temp, T) (T*)smrt_arena_push(temp.arena, sizeof(T), true)
+#define TEMP_ARENA_PUSH_ARRAY(temp, T, n) (T*)smrt_arena_push(temp.arena, sizeof(T) * (n), true)
+
 u32 plat_get_pagesize(void);
 
 void *plat_mem_reserve(u64 size);