base allocator logic

src/main.c

@@ -1,3 +1,18 @@
+#include "memory/allocator.h"
+
 int main() {
+  JLANG_memory_allocator *allocPtr = JLANG_CreateAllocator();
+
+  printf("allocatorPtr=%p\n", allocPtr);
+  printf("memoryPtr=%p\n", allocPtr->memory);
+  printf("size=%zu\n", allocPtr->size);
+
+  JLANG_visualize(allocPtr);
+
+  void *var1 = JLANG_malloc(allocPtr, 512);
+  printf("var1Ptr=%p\n", var1);
+
+  JLANG_visualize(allocPtr);
+  
   return 0;
 }

src/memory/allocator.h

@@ -0,0 +1,216 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+/*
+    Custom Memory Allocator
+
+    Implementacion custom de un memory allocator que opera sobre un array de bytes usandolo como "heap"
+*/
+
+#define JLANG_OK 0
+#define JLANG_ERR 1
+#define JLANG_FREE 0
+#define JLANG_HEADER 1
+#define JLANG_PAYLOAD 2
+
+/*
+    La estructura de Metadata se encarga de almacenar el tamaño del bloque y si está en uso.
+    Se añadirá al principio de cada bloque
+    [BLOCK_METADATA] + [BLOCK_BYTES]
+*/
+typedef struct
+{
+    size_t size; // 8 bytes
+    int in_use;  // 4 bytes
+    // --- aquí el compilador mete 4 bytes invisibles ---
+} JLANG_metadata;
+
+/*
+    La estructura de Memory Allocator se encarga de almancenar el array de memoria y el tamaño de esta.
+*/
+typedef struct
+{
+    char *memory; // 8 bytes
+    size_t size;  // 8 bytes
+} JLANG_memory_allocator;
+
+void *JLANG_CreateAllocator()
+{
+    // Allocate memory in heap for JLANG_memory_allocator
+    JLANG_memory_allocator *allocator = (JLANG_memory_allocator *)malloc(sizeof(JLANG_memory_allocator));
+
+    // Assign default free bytes
+    allocator->memory = (char *)malloc(1 * 1024);
+    allocator->size = 1 * 1024;
+
+    // ensure all memory is zero
+    for (int i = 0; i < 1 * 1024; i++)
+    {
+        allocator->memory[i] = 0;
+    }
+
+    return allocator;
+}
+
+size_t JLANG_used(void *ptr)
+{
+    JLANG_memory_allocator *allocPtr = (JLANG_memory_allocator *)ptr;
+
+    // Iterate memory parsing only metadata
+    JLANG_metadata *currentHeader = (JLANG_metadata *)allocPtr->memory;
+    size_t used = 0;
+    while (currentHeader->in_use != 0 && used < allocPtr->size)
+    {
+        used += sizeof(JLANG_metadata) + currentHeader->size;
+
+        // Current block is in_use, jump to next block
+        currentHeader = (JLANG_metadata *)((char *)currentHeader + sizeof(JLANG_metadata) + currentHeader->size);
+    }
+
+    return used;
+}
+
+void *JLANG_last_free(void *ptr)
+{
+    JLANG_memory_allocator *allocPtr = (JLANG_memory_allocator *)ptr;
+
+    // Iterate memory parsing only metadata
+    JLANG_metadata *currentHeader = (JLANG_metadata *)allocPtr->memory;
+    size_t used = 0;
+    while (currentHeader->in_use != 0 && used < allocPtr->size)
+    {
+        used += sizeof(JLANG_metadata) + currentHeader->size;
+
+        // Current block is in_use, jump to next block
+        currentHeader = (JLANG_metadata *)((char *)currentHeader + sizeof(JLANG_metadata) + currentHeader->size);
+    }
+
+    return currentHeader;
+}
+
+void *JLANG_malloc(void *ptr, size_t size)
+{
+    JLANG_memory_allocator *allocPtr = (JLANG_memory_allocator *)ptr;
+
+    // 1. Hay bloques disponibles??
+    size_t used = JLANG_used(ptr);
+    size_t available = allocPtr->size - used;
+
+    // chequear si hay suficiente espacio libre
+    if (available > size + sizeof(JLANG_metadata))
+    {
+        JLANG_metadata *freeHeader = (JLANG_metadata *)JLANG_last_free(ptr);
+        freeHeader->size = size;
+        freeHeader->in_use = 1;
+
+        return (char *)freeHeader + sizeof(JLANG_metadata);
+    }
+
+    return NULL; // TODO
+}
+
+/*
+    Debug Visualization
+
+    [FF FF FF FF FF FF FF ]
+*/
+
+int _ceil(float v)
+{
+    int n = (int)v;
+    float r = v - n;
+
+    if (r > 0)
+    {
+        return n + 1;
+    }
+    return n;
+}
+
+void JLANG_visualize(void *ptr)
+{
+    JLANG_memory_allocator *allocPtr = (JLANG_memory_allocator *)ptr;
+
+    // Step 1. Get byte type
+    char *byteMapPtr = (char *)malloc(allocPtr->size);
+    memset(byteMapPtr, 0, allocPtr->size);
+
+    JLANG_metadata *currentHeader = (JLANG_metadata *)allocPtr->memory;
+    long used = 0;
+    while (used < allocPtr->size)
+    {
+        long blockIndex = (char *)currentHeader - (char *)allocPtr->memory;
+        printf("blockIndex=%u\n", blockIndex);
+        used += sizeof(JLANG_metadata) + currentHeader->size;
+        
+        /*
+            HEADER
+            blockIndex + sizeof(JLANG_metadata)
+        */
+
+        if (currentHeader->size > 0)
+        {
+            byteMapPtr[blockIndex] = JLANG_HEADER;
+            for (int i = 0; i < sizeof(JLANG_metadata); i++)
+            {
+                byteMapPtr[blockIndex + i] = JLANG_HEADER;
+            }
+
+            /*
+                PAYLOAD
+            */
+            for (int i = 0; i < currentHeader->size; i++)
+            {
+                byteMapPtr[blockIndex + sizeof(JLANG_metadata) + i] = JLANG_PAYLOAD;
+            }
+        } else {
+            break;
+        }
+
+        // Jump to next block
+        currentHeader = (JLANG_metadata *)((char *)currentHeader + sizeof(JLANG_metadata) + currentHeader->size);
+    }
+
+    // Step 2. Draw
+
+    int bytePerRow = 40;
+    int totalRows = _ceil(allocPtr->size / bytePerRow);
+    printf("totalRows=%d\n", totalRows);
+
+    char *currentMemPtr = allocPtr->memory;
+
+    for (int i = 0; i < totalRows; i++)
+    {
+        printf("[");
+        for (int n = 0; n < bytePerRow; n++)
+        {
+
+            int index = n + i * bytePerRow;
+
+            switch (byteMapPtr[index])
+            {
+            case JLANG_HEADER:
+                printf("\033[46m");
+                break;
+            case JLANG_FREE:
+                printf("\033[32m");
+                break;
+            default:
+                printf("\033[41m");
+                break;
+            }
+
+            printf("%.2x", (unsigned char) *(currentMemPtr + (n + i * bytePerRow)));
+
+            if (n < bytePerRow - 1)
+            {
+                printf(" ");
+            }
+
+            printf("\033[0m");
+        }
+
+        printf("]\n");
+    }
+}