Initialize PFA and mark available memory

include/kernaux/pfa.h

@@ -1,10 +1,31 @@
 #ifndef KERNAUX_INCLUDED_PFA
 #define KERNAUX_INCLUDED_PFA 1
 
+#include <kernaux/stdlib.h>
+
+#define KERNAUX_PFA_PAGE_SIZE (4 * 1024)
+#define KERNAUX_PFA_PAGES_COUNT_MAX (1024 * 1024)
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 
+struct KernAux_PFA {
+    kernaux_bool pages[KERNAUX_PFA_PAGES_COUNT_MAX];
+};
+
+void KernAux_PFA_initialize(
+    struct KernAux_PFA *pfa
+)
+__attribute__((nonnull));
+
+void KernAux_PFA_mark_available(
+    struct KernAux_PFA *pfa,
+    unsigned int start,
+    unsigned int end
+)
+__attribute__((nonnull));
+
 #ifdef __cplusplus
 }
 #endif

src/pfa.c

@@ -1,3 +1,37 @@
 #include "config.h"
 
 #include <kernaux/pfa.h>
+#include <kernaux/stdlib.h>
+
+void KernAux_PFA_initialize(struct KernAux_PFA *const pfa)
+{
+    kernaux_memset(pfa->pages, KERNAUX_FALSE, sizeof(pfa->pages));
+}
+
+void KernAux_PFA_mark_available(
+    struct KernAux_PFA *const pfa,
+    unsigned int start,
+    unsigned int end
+) {
+    if (start >= end) {
+        return;
+    }
+
+    const unsigned int start_rem = start % KERNAUX_PFA_PAGE_SIZE;
+    const unsigned int end_rem = (end + 1) % KERNAUX_PFA_PAGE_SIZE;
+
+    if (start_rem != 0) {
+        start = start - start_rem + KERNAUX_PFA_PAGE_SIZE;
+    }
+
+    if (end_rem != 0) {
+        end = end - end_rem;
+    }
+
+    const unsigned int start_index = start / KERNAUX_PFA_PAGE_SIZE;
+    const unsigned int end_index   = end   / KERNAUX_PFA_PAGE_SIZE;
+
+    for (unsigned int index = start_index; index <= end_index; ++index) {
+        pfa->pages[index] = KERNAUX_TRUE;
+    }
+}

tests/test_pfa.c

@@ -4,5 +4,36 @@
 
 int main()
 {
+    struct KernAux_PFA pfa;
+
+    KernAux_PFA_initialize(&pfa);
+
+    for (unsigned int index = 0; index < KERNAUX_PFA_PAGES_COUNT_MAX; ++index) {
+        assert(pfa.pages[index] == KERNAUX_FALSE);
+    }
+
+    KernAux_PFA_mark_available(&pfa, 0, 654335);
+    KernAux_PFA_mark_available(&pfa, 1048576, 134086655);
+
+    for (unsigned int index = 0; index < 159; ++index) {
+        assert(pfa.pages[index] == KERNAUX_TRUE);
+    }
+
+    for (unsigned int index = 159; index < 256; ++index) {
+        assert(pfa.pages[index] == KERNAUX_FALSE);
+    }
+
+    for (unsigned int index = 256; index < 32736; ++index) {
+        assert(pfa.pages[index] == KERNAUX_TRUE);
+    }
+
+    for (
+        unsigned int index = 32736;
+        index < KERNAUX_PFA_PAGES_COUNT_MAX;
+        ++index
+    ) {
+        assert(pfa.pages[index] == KERNAUX_FALSE);
+    }
+
     return 0;
 }