Minor updates

build.sh

@@ -1,3 +1,3 @@
 #!/bin/sh
 set -x
-clang-19  -pipe -fsanitize=address -ggdb -Wall -Wextra -Wno-unused-parameter -Wno-unused-variable -std=gnu23 $CFLAGS src/*c
+clang-19 -DDEBUG -pipe -fsanitize=address -ggdb -Wall -Wextra -Wno-unused-parameter -Wno-unused-variable -std=gnu23 $CFLAGS src/*c

src/arena.c

@@ -13,13 +13,8 @@ Arena *arena_alloc(const ArenaParams *params)
     Assert(params->size > ARENA_HEADER_SZ);
     Assert(params->size < (U32_Max -  ARENA_HEADER_SZ - 1));
 
-    // Note: only backend now is malloc
     void *base;
-    if (params->flags & ArenaFlag_UseMalloc){
-        base = platform_malloc(params->size);
-    }  else {
     base = memory_allocate(params->size);
-    }
     Assert(base != NULL);
     ASAN_UNPOISON_MEMORY_REGION(base, ARENA_HEADER_SZ);
 
@@ -43,11 +38,7 @@ void arena_free(Arena *arena)
 
     while (it != NULL) {
         Arena *prev = it->prev;
-        if (it->flags & ArenaFlag_UseMalloc){
-            platform_free(it->base);
-        }  else {
         memory_free(it->base, it->size);
-        }
         it = prev;
     }
 }
@@ -98,12 +89,7 @@ void arena_pop_to(Arena *arena, U32 abs_pos)
 
         if (current->base_pos >= abs_pos) {
             ASAN_UNPOISON_MEMORY_REGION(current->base, current->size); // needed as we use malloc
-            if (current->flags & ArenaFlag_UseMalloc){
-                platform_free(current->base);
-            }  else {
             memory_free(current->base, current->size);
-            }
-
             arena->current = prev;
         } else {
             U32 new_pos = abs_pos - current->base_pos;

src/arena.h

@@ -2,10 +2,7 @@
 #include "base_core.h"
 
 
-typedef U32 ArenaFlags;
+typedef U32 ArenaFlags; // no flags defined yets
-enum {
-  ArenaFlag_UseMalloc = (1 << 0),
-};
 
 typedef struct ArenaParams ArenaParams;
 struct ArenaParams {

src/main.c

@@ -43,7 +43,6 @@ static void arena_test_2(void)
 {
     ArenaParams arena_params = {};
     arena_params.size = 1024+ARENA_HEADER_SZ;
-    arena_params.flags = ArenaFlag_UseMalloc;
     Arena *arena = arena_alloc(&arena_params);
 
     void *ptr;

src/platform.c

@@ -1,8 +1,31 @@
 #include "base_core.h"
 #include <stdlib.h>
+#include <stdio.h>
 #include <unistd.h>
 #include <sys/mman.h>
 
+
+U32 platform_page_size(void)
+{
+    return getpagesize();
+}
+
+static INLINE size_t AlignToPageSize(size_t sz)
+{
+    U32 page_size = platform_page_size();
+    size_t aligned_sz = AlignUpPow2(sz, page_size);
+
+    return aligned_sz;
+}
+
+static INLINE size_t AlignToPageStart(size_t sz)
+{
+    U32 page_size = platform_page_size();
+    size_t aligned_sz = AlignDownPow2(sz, page_size);
+
+    return aligned_sz;
+}
+
 void *platform_malloc(size_t sz)
 {
     return malloc(sz);
@@ -16,10 +39,13 @@ void platform_free(void *mem)
 
 void *memory_allocate(size_t sz)
 {
-    int page_size = getpagesize();
+    if (sz == 0) {
-    size_t aligned_sz = AlignUpPow2(sz, page_size);
+        sz = 1;
+    }
 
+    size_t aligned_sz = AlignToPageSize(sz);
     void *mem = mmap(0, aligned_sz, PROT_READ | PROT_WRITE, MAP_ANONYMOUS  | MAP_PRIVATE, -1, 0);
+    TRACEF("memory_allocate size=%zu aligned_size=%zu mem=%p\n", sz, aligned_sz, mem);
     if (mem == MAP_FAILED) {
         mem = NULL;
     }
@@ -28,10 +54,36 @@ void *memory_allocate(size_t sz)
 
 void memory_free(void *mem, size_t sz)
 {
-    int page_size = getpagesize();
+    size_t aligned_sz = AlignToPageSize(sz);
-    size_t aligned_sz = AlignUpPow2(sz, page_size);
+    TRACEF("        memory_free     size=%zu aligned_size=%zu mem=%p\n", sz, aligned_sz, mem);
 
     int rc = munmap(mem, aligned_sz);
 
     Assert(rc == 0);
 }
+
+void memory_commit(void *mem, size_t sz)
+{
+    size_t aligned_sz = AlignToPageSize(sz);
+    void *aligned_mem = (void *)AlignToPageStart((uintptr_t)mem);
+    TRACEF("memory_commit size=%zu aligned_size=%zu ptr=%p aligned_mem=%p\n", sz, aligned_sz, mem, aligned_mem);
+
+    int rc;
+    rc = mprotect(aligned_mem, aligned_sz, PROT_READ | PROT_WRITE);
+    Assert(rc == 0);
+    rc = madvise(aligned_mem, aligned_sz, MADV_WILLNEED);
+    Assert(rc == 0);
+}
+
+void memory_decommit(void *mem, size_t sz)
+{
+    size_t aligned_sz = AlignToPageSize(sz);
+    void *aligned_mem = (void *)AlignToPageStart((uintptr_t)mem);
+    TRACEF("memory_commit size=%zu aligned_size=%zu ptr=%p aligned_mem=%p\n", sz, aligned_sz, mem, aligned_mem);
+
+    int rc;
+    rc = mprotect(aligned_mem, aligned_sz, PROT_NONE);
+    Assert(rc == 0);
+    rc = madvise(aligned_mem, aligned_sz, MADV_DONTNEED);
+    Assert(rc == 0);
+}

src/platform.h

@@ -3,6 +3,8 @@
 
 void *platform_malloc(size_t sz);
 void platform_free(void *mem);
+U32 platform_page_size(void);
 
 void *memory_allocate(size_t sz);
 void *memory_free(void *mem, size_t sz);
+