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+// AMR ARRAY
+// GENERAL ARRAYS FOR C
+// > Mainly for prototyping and small internal programs
+//
+// Documentation:
+//
+// AMR_MALLOC: 
+//      malloc function, can be replace with a custom allocator (todo)
+// AMR_FREE: 
+//      free function, can be replace with a custom allocator (todo)
+// amr_arr_len: 
+//      get array length
+// amr_arr_cap: 
+//      get array capacity
+// amr_arr_init:                     
+//      initialize array, see usage for how to use.
+// amr_arr_tinit:
+//      initialize array with type. gets around void cast issue, annoying on
+//      c++
+// amr_arr_push(arr, value):        
+//      push an element on to the end of an array.
+//      will not care about holes in array.
+// amr_arr_pushcarr(arr, carr):     
+//      push a c-style constant size array
+// amr_arr_join(arr_a, arr_b):
+//      join/push all items from array b into array a
+// amr_arr_clear(arr):
+//      clears array. (actually just resets the len variable of array, 
+//                     since operations first work on array len, this is all 
+//                     we need to "clear" it)
+//
+// Usage:
+//
+//  typdef T arr_t;     // optional, but recommended to signify a type is an array. 
+//                      // Highlights intent, prevents confusion
+//  
+//  int main() {
+//      arr_t *myarr;
+//      amr_arr_init(myarr, capacity);
+//
+//      amr_arr_push(myarr, 2);
+//      ...
+//  }
+
+#ifndef __AMR_INCLUDE_AMR_ARRAY_H
+#define __AMR_INCLUDE_AMR_ARRAY_H
+
+#include "stdlib.h"
+#include "assert.h"
+#include "string.h"
+
+struct ArrayHeader {
+    int len;
+    int cap;
+};
+typedef struct ArrayHeader ArrayHeader;
+
+#define __CARR_LEN(CARR) (sizeof((CARR))/sizeof((CARR)[0]))
+#define AMR_MALLOC(x) malloc((x))
+#define AMR_FREE(p) free((p))
+#define amr_arr_len(A) ((((ArrayHeader*)(A)) - 1)->len)
+#define amr_arr_cap(A) ((((ArrayHeader*)(A)) -1)->cap)
+
+#define amr_arr_init(ARR, CAP) {                                                                    \
+    ArrayHeader *H = (ArrayHeader*)AMR_MALLOC((CAP)*sizeof((ARR)[0]) + sizeof(ArrayHeader));    \
+    H->len = 0;                                                                                 \
+    H->cap = (CAP);                                                                             \
+    ARR = (void*)(H+1);                                                                         \
+}
+
+#define amr_arr_tinit(T, ARR, CAP) {                                                                    \
+    ArrayHeader *H = (ArrayHeader*)AMR_MALLOC((CAP)*sizeof((ARR)[0]) + sizeof(ArrayHeader));    \
+    H->len = 0;                                                                                 \
+    H->cap = (CAP);                                                                             \
+    ARR = (T*)(H+1);                                                                         \
+}
+
+#define amr_arr_push(ARR, VAL) {                    \
+    ArrayHeader *H = ((ArrayHeader*)(ARR)-1);   \
+    assert(H->len+1 <= H->cap);                 \
+    (ARR)[H->len++] = (VAL);                    \
+}
+
+#define amr_arr_pushcarr(ARR, ELE) {                    \
+    ArrayHeader *H = ((ArrayHeader*)(ARR)-1);       \
+    assert(H->len+(__CARR_LEN((ELE))) <= H->cap);   \
+    memcpy((ARR)+H->len, (ELE), sizeof((ELE)));     \
+    H->len += (__CARR_LEN((ELE)));                  \
+}
+
+#define amr_arr_join(A, B) {                                \
+    ArrayHeader *HA = (ArrayHeader*)(A)-1;              \
+    ArrayHeader *HB = (ArrayHeader*)(B)-1;              \
+    assert(HA->len + HB->len <= HA->cap);               \
+    memcpy((A) + HA->len, (B), sizeof((B)[0])*HB->len); \
+    HA->len += HB->len;                                 \
+}
+
+#define amr_arr_clear(ARR) {    \
+    ArrayHeader *H = (ArrayHeader*)(ARR)-1;     \
+    H->len = 0;     \
+}
+
+#define amr_arr_free(ARR) {                 \
+    AMR_FREE((ArrayHeader*)(ARR)-1);    \
+}
+
+#endif  // __AMR_INCLUDE_AMR_ARRAY_H
+
+