Re: [PATCH 3/7] inflate pt1: clean up input logic

On Fri, Feb 24, 2006 at 02:12:16PM -0600, Matt Mackall wrote:
-static const u16 mask_bits[] = {
- 0x0000,
- 0x0001, 0x0003, 0x0007, 0x000f, 0x001f, 0x003f, 0x007f, 0x00ff,
- 0x01ff, 0x03ff, 0x07ff, 0x0fff, 0x1fff, 0x3fff, 0x7fff, 0xffff
-};
+static inline u32 readbits(u32 *b, u32 *k, int n)
+{
+ for( ; *k < n; *k += 8)
+ *b |= (u32)get_byte() << *k;
+ return *b & ((1 << n) - 1);
+}

-#define NEXTBYTE() ({ int v = get_byte(); if (v < 0) goto underrun; (u8)v; })

How does this change handle the case where we run out of input data?
This condition needs to be handled explicitly because the inflate
functions can infinitely loop.

Relying on a bit pattern returned by get_byte() is how this code
pre-fix used to work, and it caused several confused bug reports.

--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of: 2.6 Serial core
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