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ngx_http_flv_module/ngx_rtmp_bitop.c

@@ -0,0 +1,63 @@
+
+/*
+ * Copyright (C) Roman Arutyunyan
+ */
+
+
+#include <ngx_config.h>
+#include <ngx_core.h>
+#include "ngx_rtmp_bitop.h"
+
+
+void
+ngx_rtmp_bit_init_reader(ngx_rtmp_bit_reader_t *br, u_char *pos, u_char *last)
+{
+    ngx_memzero(br, sizeof(ngx_rtmp_bit_reader_t));
+
+    br->pos = pos;
+    br->last = last;
+}
+
+
+uint64_t
+ngx_rtmp_bit_read(ngx_rtmp_bit_reader_t *br, ngx_uint_t n)
+{
+    uint64_t    v;
+    ngx_uint_t  d;
+
+    v = 0;
+
+    while (n) {
+
+        if (br->pos >= br->last) {
+            br->err = 1;
+            return 0;
+        }
+
+        d = (br->offs + n > 8 ? (ngx_uint_t) (8 - br->offs) : n);
+
+        v <<= d;
+        v += (*br->pos >> (8 - br->offs - d)) & ((u_char) 0xff >> (8 - d));
+
+        br->offs += d;
+        n -= d;
+
+        if (br->offs == 8) {
+            br->pos++;
+            br->offs = 0;
+        }
+    }
+
+    return v;
+}
+
+
+uint64_t
+ngx_rtmp_bit_read_golomb(ngx_rtmp_bit_reader_t *br)
+{
+    ngx_uint_t  n;
+
+    for (n = 0; ngx_rtmp_bit_read(br, 1) == 0 && !br->err; n++);
+
+    return ((uint64_t) 1 << n) + ngx_rtmp_bit_read(br, n) - 1;
+}