1 files changed, 112 insertions, 0 deletions
diff --git a/supervisor/shared/memory.c b/supervisor/shared/memory.c
new file mode 100755
index 000000000..051f55a70
--- /dev/null
+++ b/supervisor/shared/memory.c
@@ -0,0 +1,112 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2018 Scott Shawcroft for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "supervisor/memory.h"
+
+#include <stddef.h>
+
+#define CIRCUITPY_SUPERVISOR_ALLOC_COUNT 8
+
+static supervisor_allocation allocations[CIRCUITPY_SUPERVISOR_ALLOC_COUNT];
+// We use uint32_t* to ensure word (4 byte) alignment.
+uint32_t* low_address;
+uint32_t* high_address;
+extern uint32_t _ebss;
+extern uint32_t _estack;
+
+void memory_init(void) {
+    low_address = &_ebss;
+    high_address = &_estack;
+}
+
+void free_memory(supervisor_allocation* allocation) {
+    uint8_t index = 0;
+    bool found = false;
+    for (index = 0; index < CIRCUITPY_SUPERVISOR_ALLOC_COUNT; index++) {
+        found = allocation == &allocations[index];
+        if (found) {
+            break;
+        }
+    }
+    if (allocation->ptr == high_address) {
+        high_address += allocation->length / 4;
+        for (index++; index < CIRCUITPY_SUPERVISOR_ALLOC_COUNT; index++) {
+            if (allocations[index].ptr != NULL) {
+                break;
+            }
+            high_address += allocations[index].length / 4;
+        }
+    } else if (allocation->ptr + allocation->length / 4 == low_address) {
+        low_address = allocation->ptr;
+        for (index--; index >= 0; index--) {
+            if (allocations[index].ptr != NULL) {
+                break;
+            }
+            low_address -= allocations[index].length / 4;
+        }
+    } else {
+        // Freed memory isn't in the middle so skip updating bounds. The memory will be added to the
+        // middle when the memory to the inside is freed.
+    }
+    allocation->ptr = NULL;
+}
+
+supervisor_allocation* allocate_remaining_memory(void) {
+    if (low_address == high_address) {
+        return NULL;
+    }
+    return allocate_memory((high_address - low_address) * 4, false);
+}
+
+supervisor_allocation* allocate_memory(uint32_t length, bool high) {
+    if ((high_address - low_address) * 4 < (int32_t) length || length % 4 != 0) {
+        return NULL;
+    }
+    uint8_t index = 0;
+    int8_t direction = 1;
+    if (high) {
+        index = CIRCUITPY_SUPERVISOR_ALLOC_COUNT - 1;
+        direction = -1;
+    }
+    for (; index < CIRCUITPY_SUPERVISOR_ALLOC_COUNT; index += direction) {
+        if (allocations[index].ptr == NULL) {
+            break;
+        }
+    }
+    if (index >= CIRCUITPY_SUPERVISOR_ALLOC_COUNT) {
+        return NULL;
+    }
+    supervisor_allocation* alloc = &allocations[index];
+    if (high) {
+        high_address -= length / 4;
+        alloc->ptr = high_address;
+    } else {
+        alloc->ptr = low_address;
+        low_address += length / 4;
+    }
+    alloc->length = length;
+    return alloc;
+}