mmmmh

vmem.c

@@ -0,0 +1,133 @@
+#include "vmem.h"
+
+#include <assert.h>
+
+#include "tracelog.h"
+
+static usize vmem__page_size = 0;
+static void vmem__update_page_size(void);
+
+// platform generic functions
+
+usize vmemGetPageSize(void) {
+    if (!vmem__page_size) {
+        vmem__update_page_size();
+    }
+    return vmem__page_size;
+}
+
+usize vmemPadToPage(usize byte_count) {
+    if (!vmem__page_size) {
+        vmem__update_page_size();
+    }
+
+    if (byte_count == 0) {
+        return vmem__page_size;
+    }
+
+    // bit twiddiling, vmem__page_size MUST be a power of 2
+    usize padding = vmem__page_size - (byte_count & (vmem__page_size - 1));
+    if (padding == vmem__page_size) {
+        padding = 0;
+    }
+    return byte_count + padding;
+}
+
+#if COLLA_WIN
+
+#include <windows.h>
+
+void *vmemInit(usize size, usize *out_padded_size) {
+    usize alloc_size = vmemPadToPage(size);
+
+    void *ptr = VirtualAlloc(NULL, alloc_size, MEM_RESERVE, PAGE_NOACCESS);
+
+    if (out_padded_size) {
+        *out_padded_size = alloc_size;
+    }
+
+    return ptr;
+}
+
+bool vmemRelease(void *base_ptr) {
+    return VirtualFree(base_ptr, 0, MEM_RELEASE);
+}
+
+bool vmemCommit(void *ptr, usize num_of_pages) {
+    usize page_size = vmemGetPageSize();
+
+    void *new_ptr = VirtualAlloc(ptr, num_of_pages * page_size, MEM_COMMIT, PAGE_READWRITE);
+    
+    if (!new_ptr) {
+        debug("ERROR: failed to commit memory: %lu\n", GetLastError());
+    }
+
+    return new_ptr != NULL;
+}
+
+static void vmem__update_page_size(void) {
+    SYSTEM_INFO info = {0};
+    GetSystemInfo(&info);
+    vmem__page_size = info.dwPageSize;
+}
+
+// #elif COLLA_LIN
+#else
+
+#include <sys/mman.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+
+typedef struct {
+    usize len;
+} vmem__header;
+
+void *vmemInit(usize size, usize *out_padded_size) {
+    size += sizeof(vmem__header);
+    usize alloc_size = vmemPadToPage(size);
+
+    vmem__header *header = mmap(NULL, alloc_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+
+    if (header == MAP_FAILED) {
+        fatal("could not map %zu memory: %s", size, strerror(errno));
+    }
+
+    if (out_padded_size) {
+        *out_padded_size = alloc_size;
+    }
+
+    header->len = alloc_size;
+
+    return header + 1;
+}
+
+bool vmemRelease(void *base_ptr) {
+    if (!base_ptr) return false;
+    vmem__header *header = (vmem__header *)base_ptr - 1;
+
+    int res = munmap(header, header->len);
+    if (res == -1) {
+        err("munmap failed: %s", strerror(errno));
+    }
+    return res != -1;
+}
+
+bool vmemCommit(void *ptr, usize num_of_pages) {
+    // mmap doesn't need a commit step
+    (void)ptr;
+    (void)num_of_pages;
+    return true;
+}
+
+static void vmem__update_page_size(void) {
+    long lin_page_size = sysconf(_SC_PAGE_SIZE);
+
+    if (lin_page_size < 0) {
+        fatal("could not get page size: %s", strerror(errno));
+    }
+
+    vmem__page_size = (usize)lin_page_size;
+}
+
+#endif