# let's pretend we are free, for a while

在教室前面发现了这个。接下来是一个(天真的)实现ORM的尝试。我还是不明白他为什么这么写。

//这将为我们每个用户节省0.5秒，并取悦机器精神。

在很长的程序之前:)

// This should fix something that should never happen

Re eating one's own dogfood: We have the same term in our workplace (granted, only because I introduced it). My code is peppered with comments that say "TODO" and indicate something that ought to be done eventually, but a comment saying "DOGFOOD" (both keywords are always at the beginning of the comment, in all caps) means something that must be done before this program can be used even internally. It's a handy thing to search for, as the word "dogfood" is never going to appear in a quoted string - if it does, I can always just say "dog-food" or something - so even a case-insensitive search will come up with the right results.

Regarding zeroing the accumulator: I've done exactly the same thing when programming an Intel 80x86 (I started on the 8086 and moved up from there into the modern Pentiums). XORing a register with itself is the quickest and tightest way to clear it. Using "MOV AX,0" requires three bytes (opcode and two bytes of literal 16-bit zero), whereas "XOR AX,AX" is only two; it's even more noticeable with the 386-and-higher extended registers, where "MOV EAX,0" requires five bytes (four bytes of 32-bit zero). My C/C++ compiler always zeroes registers this way, so I'd assume it's still the best way (although I haven't studied opcode timing tables in ages, and probably both XOR reg,reg and MOV reg,imm take one clock).

我看到一些旧的fortran代码:

     integer *4 one,two,three;

c    asssign one to 100 before entering the loop
     one=100;

在drivers/net/sunhme.c (Linux内核)中:

/* Welcome to Sun Microsystems, can I take your order please? */
if(!hp->happy_flags & HFLAG_FENABLE)
        return happy_meal_bb_write(hp, tregs, reg, value);

/* Would you like fries with that? */
hme_write32(hp, &tregs->frame,
            (FRAME_WRITE | (hp->paddr << 23) |
             ((reg & 0xff) << 18) | (value & 0xffff)));
while(!(hme_read32(hp, &tregs->frame) & 0x10000) && --tries)
        udelay(20);

/* Anything else? */
if(!tries)
        printk(KERN_ERR "happy meal: Aieee, transceiver MIF write bolixed\n");

/* Fifty-two cents is your change, have a nice day. */