calc

commit bf20c5c23810b4a852423febc93931293b4d0f93
parent b2a64e2fba3f7ad8b9ad55fcb0c718d4eb9c7859
Author: amin <dev@aminmesbah.com>
Date:   Sat, 27 Oct 2018 03:46:24 +0000

Make a stretchy buf

FossilOrigin-Name: 28b3afc7914d9a89e792c00999e749d9fd5b25c01e992e13954ed9289378826d
Diffstat:
M
calc.c
 | 
57
++++++++++++++++++++++++++++++++++++++++++++++++++++++++-

1 file changed, 56 insertions(+), 1 deletion(-)
diff --git a/calc.c b/calc.c
@@ -1,6 +1,61 @@
+#include <assert.h>
+#include <stddef.h>
+#include <stdint.h>
 #include <stdio.h>
+#include <stdlib.h>
+
+struct BufHdr {
+    size_t cap;
+    size_t len;
+    uint8_t buf[];
+};
+
+#define buf__hdr(b) ((struct BufHdr *)((uint8_t *)(b) - offsetof(struct BufHdr, buf)))
+#define buf_cap(b) ((b) ? buf__hdr(b)->cap : 0)
+#define buf_len(b) ((b) ? buf__hdr(b)->len : 0)
+
+#define buf__must_grow(b, n) (buf_len(b) + (n) >= buf_cap(b))
+#define buf__maybe_grow(b, n) (buf__must_grow((b), (n)) ? (b) = buf__grow((b), buf_len(b) + (n), sizeof(*(b))) : 0)
+#define buf_push(b, x) (buf__maybe_grow((b), 1), (b)[buf__hdr(b)->len++] = (x))
+
+#define MAX(x, y) ((x) >= (y) ? (x) : (y))
+
+void *buf__grow(void *buf, size_t new_length, size_t element_size)
+{
+    size_t new_cap = MAX(1 + (2 * buf_cap(buf)), new_length);
+    assert(new_cap >= new_length);
+    size_t new_size = offsetof(struct BufHdr, buf) + (new_cap * element_size);
+    struct BufHdr *new_hdr = NULL;
+    if (buf)
+    {
+        new_hdr = realloc(buf__hdr(buf), new_size);
+    }
+    else
+    {
+        new_hdr = malloc(new_size);
+        new_hdr->len = 0;
+    }
+    new_hdr->cap = new_cap;
+    return new_hdr->buf;
+}
+
+void buf_test(void)
+{
+    int *buf = NULL;
+    assert(buf_len(buf) == 0);
+    for (size_t i = 0; i < 1000; ++i)
+    {
+        buf_push(buf, i);
+    }
+    assert(buf_len(buf) == 1000);
+    for (size_t i = 0; i < buf_len(buf); ++i)
+    {
+        printf("%d, ", buf[i]);
+    }
+    printf("\n");
+}
 
 int main(void)
 {
-    printf("Hello, world");
+    buf_test();
 }