69 	void *base, *begin, *end;  in perf_event_read()  local
78 	begin = base + data_tail % buffer_size;  in perf_event_read()
81 	while (begin != end) {  in perf_event_read()
84 		e = begin;  in perf_event_read()
85 		if (begin + e->header.size > base + buffer_size) {  in perf_event_read()
86 			long len = base + buffer_size - begin;  in perf_event_read()
89 			memcpy(buf, begin, len);  in perf_event_read()
92 			begin = base + e->header.size - len;  in perf_event_read()
93 		} else if (begin + e->header.size == base + buffer_size) {  in perf_event_read()
94 			begin = base;  in perf_event_read()
96 			begin += e->header.size;  in perf_event_read()