From c24c1d160702f227cede324999bb5fbd15c7f312 Mon Sep 17 00:00:00 2001
From: Aryadev Chavali <aryadev@aryadevchavali.com>
Date: Sun, 15 Oct 2023 21:49:30 +0100
Subject: Implemented a dynamically sized byte array

Pretty simple, want to ensure amortised constant big O so I use a
REALLOC_MULT, which can be redefined if wished.
---
 Makefile   |  2 +-
 src/darr.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/darr.h | 35 +++++++++++++++++++++++++++++++++++
 3 files changed, 94 insertions(+), 1 deletion(-)
 create mode 100644 src/darr.c
 create mode 100644 src/darr.h

diff --git a/Makefile b/Makefile
index a89b547..566f41a 100644
--- a/Makefile
+++ b/Makefile
@@ -7,7 +7,7 @@ OUT=ovm.out
 SRC=src
 DIST=build
 
-CODE=$(addprefix $(SRC)/, runtime.c main.c)
+CODE=$(addprefix $(SRC)/, darr.c runtime.c main.c)
 OBJECTS=$(CODE:$(SRC)/%.c=$(DIST)/%.o)
 DEPS=$(OBJECTS:%.o=%.d)
 
diff --git a/src/darr.c b/src/darr.c
new file mode 100644
index 0000000..1a55ea5
--- /dev/null
+++ b/src/darr.c
@@ -0,0 +1,58 @@
+/* Copyright (C) 2023 Aryadev Chavali
+
+ * You may distribute and modify this code under the terms of the
+ * GPLv2 license.  You should have received a copy of the GPLv2
+ * license with this file.  If not, please write to:
+ * aryadev@aryadevchavali.com.
+
+ * Created: 2023-10-15
+ * Author: Aryadev Chavali
+ * Description: Dynamically sized byte array
+ */
+
+#include <malloc.h>
+#include <string.h>
+
+#include "./darr.h"
+
+void darr_init(darr_t *darr, size_t size)
+{
+  if (size == 0)
+    size = DARR_DEFAULT_SIZE;
+  *darr = (darr_t){
+      .data      = calloc(size, 1),
+      .used      = 0,
+      .available = size,
+  };
+}
+
+void darr_ensure_capacity(darr_t *darr, size_t requested)
+{
+  if (darr->used + requested >= darr->available)
+  {
+    darr->available =
+        MAX(darr->used + requested, darr->available * DARR_REALLOC_MULT);
+    darr->data = realloc(darr->data, darr->available);
+  }
+}
+
+void darr_append_byte(darr_t *darr, byte byte)
+{
+  darr_ensure_capacity(darr, 1);
+  darr->data[darr->used++] = byte;
+}
+
+void darr_append_bytes(darr_t *darr, byte *bytes, size_t n)
+{
+  darr_ensure_capacity(darr, n);
+  memcpy(darr->data + darr->used, bytes, n);
+  darr->used += n;
+}
+
+byte darr_at(darr_t *darr, size_t index)
+{
+  if (index >= darr->used)
+    // TODO: Error (index is out of bounds)
+    return 0;
+  return darr->data[index];
+}
diff --git a/src/darr.h b/src/darr.h
new file mode 100644
index 0000000..e3103ea
--- /dev/null
+++ b/src/darr.h
@@ -0,0 +1,35 @@
+/* Copyright (C) 2023 Aryadev Chavali
+
+ * You may distribute and modify this code under the terms of the
+ * GPLv2 license.  You should have received a copy of the GPLv2
+ * license with this file.  If not, please write to:
+ * aryadev@aryadevchavali.com.
+
+ * Created: 2023-10-15
+ * Author: Aryadev Chavali
+ * Description: Dynamically sized byte array
+ */
+
+#ifndef DARR_H
+#define DARR_H
+
+#include <stdlib.h>
+
+#include "./base.h"
+
+typedef struct
+{
+  byte *data;
+  size_t used, available;
+} darr_t;
+
+#define DARR_DEFAULT_SIZE 8
+#define DARR_REALLOC_MULT 1.5
+
+void darr_init(darr_t *, size_t);
+void darr_ensure_capacity(darr_t *, size_t);
+void darr_append_byte(darr_t *, byte);
+void darr_append_bytes(darr_t *, byte *, size_t);
+byte darr_at(darr_t *, size_t);
+
+#endif
-- 
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