From 98c7db3f13e5f382867551da4f4d0d07992720fe Mon Sep 17 00:00:00 2001
From: Alex Kotov <kotovalexarian@gmail.com>
Date: Tue, 14 Dec 2021 05:39:54 +0500
Subject: [PATCH] Allocate and free multiple pages in PFA

---
 include/kernaux/pfa.h |  6 ++++++
 src/pfa.c             | 45 +++++++++++++++++++++++++++++++++++++++++--
 tests/test_pfa.c      | 34 ++++++++++++++++++++++++++------
 3 files changed, 77 insertions(+), 8 deletions(-)

diff --git a/include/kernaux/pfa.h b/include/kernaux/pfa.h
index fe9fb9d..8fe0af2 100644
--- a/include/kernaux/pfa.h
+++ b/include/kernaux/pfa.h
@@ -32,9 +32,15 @@ __attribute__((nonnull));
 size_t KernAux_PFA_alloc_page(KernAux_PFA pfa)
 __attribute__((nonnull));
 
+size_t KernAux_PFA_alloc_pages(KernAux_PFA pfa, size_t mem_size)
+__attribute__((nonnull));
+
 void KernAux_PFA_free_page(KernAux_PFA pfa, size_t page_addr)
 __attribute__((nonnull));
 
+void KernAux_PFA_free_pages(KernAux_PFA pfa, size_t page_addr, size_t mem_size)
+__attribute__((nonnull));
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/pfa.c b/src/pfa.c
index 6d66bd2..82c9ece 100644
--- a/src/pfa.c
+++ b/src/pfa.c
@@ -71,8 +71,7 @@ void KernAux_PFA_mark(
 size_t KernAux_PFA_alloc_page(const KernAux_PFA pfa)
 {
     // We start from 1 because 0 indicates failure.
-    // It is not very usefull to alloc page at address 0;
-    //
+    // It is not very useful to alloc page at address 0;
     for (size_t index = 1; index < KERNAUX_PFA_PAGES_COUNT_MAX; ++index) {
         if (pfa->pages[index]) {
             pfa->pages[index] = false;
@@ -83,9 +82,51 @@ size_t KernAux_PFA_alloc_page(const KernAux_PFA pfa)
     return 0;
 }
 
+size_t KernAux_PFA_alloc_pages(const KernAux_PFA pfa, const size_t mem_size)
+{
+    if (mem_size % KERNAUX_PFA_PAGE_SIZE != 0) return 0;
+
+    const size_t pages_count = mem_size  / KERNAUX_PFA_PAGE_SIZE;
+
+    // We start from 1 because 0 indicates failure.
+    // It is not very useful to alloc page at address 0;
+    for (size_t start = 1; start < KERNAUX_PFA_PAGES_COUNT_MAX;) {
+        size_t end = start;
+        for (; end < start + pages_count; ++end) {
+            if (!pfa->pages[end]) break;
+        }
+        if (end >= KERNAUX_PFA_PAGES_COUNT_MAX) return 0;
+        if (end == start + pages_count - 1) {
+            for (size_t index = start; index <= end; ++index) {
+                pfa->pages[index] = false;
+            }
+            return start * KERNAUX_PFA_PAGE_SIZE;
+        }
+        start = end + 1;
+    }
+
+    return 0;
+}
+
 void KernAux_PFA_free_page(const KernAux_PFA pfa, size_t page_addr)
 {
     if (page_addr % KERNAUX_PFA_PAGE_SIZE != 0) return;
 
     pfa->pages[page_addr / KERNAUX_PFA_PAGE_SIZE] = true;
 }
+
+void KernAux_PFA_free_pages(
+    const KernAux_PFA pfa,
+    const size_t page_addr,
+    const size_t mem_size
+) {
+    if (page_addr % KERNAUX_PFA_PAGE_SIZE != 0) return;
+    if (mem_size  % KERNAUX_PFA_PAGE_SIZE != 0) return;
+
+    const size_t start_index = page_addr / KERNAUX_PFA_PAGE_SIZE;
+    const size_t pages_count = mem_size  / KERNAUX_PFA_PAGE_SIZE;
+
+    for (size_t index = 0; index < pages_count; ++index) {
+        pfa->pages[start_index + index] = true;
+    }
+}
diff --git a/tests/test_pfa.c b/tests/test_pfa.c
index 892e8a9..23ba21b 100644
--- a/tests/test_pfa.c
+++ b/tests/test_pfa.c
@@ -44,15 +44,37 @@ int main()
         assert(!KernAux_PFA_is_available(&pfa, index * KERNAUX_PFA_PAGE_SIZE));
     }
 
-    const size_t page_addr = KernAux_PFA_alloc_page(&pfa);
+    {
+        const size_t page_addr = KernAux_PFA_alloc_page(&pfa);
 
-    assert(page_addr != 0);
-    assert(page_addr % KERNAUX_PFA_PAGE_SIZE == 0);
-    assert(!KernAux_PFA_is_available(&pfa, page_addr));
+        assert(page_addr != 0);
+        assert(page_addr % KERNAUX_PFA_PAGE_SIZE == 0);
+        assert(!KernAux_PFA_is_available(&pfa, page_addr));
 
-    KernAux_PFA_free_page(&pfa, page_addr);
+        KernAux_PFA_free_page(&pfa, page_addr);
 
-    assert(KernAux_PFA_is_available(&pfa, page_addr));
+        assert(KernAux_PFA_is_available(&pfa, page_addr));
+    }
+
+    {
+        const size_t page_addr =
+            KernAux_PFA_alloc_pages(&pfa, 10 * KERNAUX_PFA_PAGE_SIZE);
+
+        assert(page_addr != 0);
+        assert(page_addr % KERNAUX_PFA_PAGE_SIZE == 0);
+
+        for (size_t index = 0, addr = page_addr; index < 10; ++index) {
+            assert(!KernAux_PFA_is_available(&pfa, addr));
+            addr += KERNAUX_PFA_PAGE_SIZE;
+        }
+
+        KernAux_PFA_free_pages(&pfa, page_addr, 10 * KERNAUX_PFA_PAGE_SIZE);
+
+        for (size_t index = 0, addr = page_addr; index < 10; ++index) {
+            assert(KernAux_PFA_is_available(&pfa, addr));
+            addr += KERNAUX_PFA_PAGE_SIZE;
+        }
+    }
 
     for (size_t index = 0; index < KERNAUX_PFA_PAGES_COUNT_MAX; ++index) {
         if (KernAux_PFA_is_available(&pfa, index * KERNAUX_PFA_PAGE_SIZE)) {