From de40227d08f47946904a074a9408d35a8a3cbd1b Mon Sep 17 00:00:00 2001
From: Themis Demetriades <td1223@ic.ac.uk>
Date: Thu, 30 May 2024 14:17:43 +0100
Subject: [PATCH] Add binary file loading w/ S

---
 src/fileio.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 src/fileio.h |  9 +++++++++
 2 files changed, 56 insertions(+)
 create mode 100644 src/fileio.c
 create mode 100644 src/fileio.h

diff --git a/src/fileio.c b/src/fileio.c
new file mode 100644
index 0000000..b8c0574
--- /dev/null
+++ b/src/fileio.c
@@ -0,0 +1,47 @@
+#include <assert.h>
+#include <stdio.h>
+#include <string.h>
+#include "fileio.h"
+
+/* Loads a binary file located at filePath to memory, taking up a block of exactly memorySize bytes,
+   and returns the starting address of the data. If memorySize is insufficient to store the entire file,
+   an appropriate error is reported. Excess memory is set to 0 bit values. */
+
+word *fileio_loadBin(const char *filePath, size_t memorySize) {
+    FILE *file = fopen(filePath, "rb");
+    if (file == NULL) {
+        fprintf(stderr, "Couldn't open %s!\n", filePath);
+        exit(EXIT_FAILURE);
+    }
+
+    word *fileData = malloc(memorySize);
+    if (fileData == NULL) {
+        fprintf(stderr, "Ran out of memory attempting to load %s!\n", filePath);
+        exit(EXIT_FAILURE);
+    }
+
+    // Loop while reading from the file yields data. Only terminates if EOF is reached or ERROR occurs.
+    // Explicitly deal with attempting to write too much data to memory block, rather than allow segfault.
+    const size_t wordCount = memorySize/sizeof(word);
+    int i = 0;
+    while (fread(fileData + i, sizeof(word), 1, file)) {
+        if (i >= wordCount) {
+            fprintf(stderr, "Attempting to load binary %s to memory of smaller size %zu!\n", filePath, memorySize);
+            exit(EXIT_FAILURE);
+        }
+
+        i++;
+    }
+
+    if (ferror(file)) {
+        fprintf(stderr, "Encountered error attempting to read %s!\n", filePath);
+        exit(EXIT_FAILURE);
+    }
+    assert(fclose(file) != EOF);
+
+    // If part of memory block was left uninitialized, initialize it to zero.
+    if (i < wordCount) {
+        memset(fileData + i, 0, (wordCount - i) * sizeof(word));   
+    }
+    return fileData;
+}
diff --git a/src/fileio.h b/src/fileio.h
new file mode 100644
index 0000000..8a439bf
--- /dev/null
+++ b/src/fileio.h
@@ -0,0 +1,9 @@
+#ifndef __FILEIO__
+#define __FILEIO__
+#include <stdlib.h>
+#include "global.h"
+
+#define EXIT_FAILURE 1
+
+extern word *fileio_loadBin(const char *filePath, size_t memorySize);
+#endif