aura_buffer_scan_char
char aura_buffer_scan_char(struct aura_buffer *);
c = aura_buffer_scan_char(e);
len = len * 10 + aura_buffer_scan_char(e) - '0';
str[i++] = aura_buffer_scan_char(e);
x = x * 10 + aura_buffer_scan_char(e) - '0';