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69 lines
1.7 KiB
C
69 lines
1.7 KiB
C
#ifndef _checksum_h_
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#define _checksum_h_
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#include "syn68k_private.h"
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#ifdef CHECKSUM_BLOCKS
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#include "block.h"
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extern uint32 compute_block_checksum (const Block *b);
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#ifdef INLINE_CHECKSUM
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#include "callback.h"
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static __inline__ uint32
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inline_compute_block_checksum (const Block *b)
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{
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const uint16 *code;
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uint32 sum;
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long n;
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syn68k_addr_t start;
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/* Don't actually checksum the bytes at a callback! */
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start = b->m68k_start_address;
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if (IS_CALLBACK (start))
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return (start
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+ (unsigned long) callback_argument (start)
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+ (unsigned long) callback_function (start));
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else if (start >= MAGIC_ADDRESS_BASE
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&& start < CALLBACK_STUB_BASE)
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return 0;
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code = SYN68K_TO_US (start);
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for (sum = 0, n = b->m68k_code_length / sizeof (uint16); --n >= 0; )
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{
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/* Bizarre but fast checksum. A good checksum like CRC is
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* probably too slow.
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*/
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#if defined (__GNUC__) && defined(i386)
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uint32 tmp1, tmp2;
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/* This is taking lots of CPU time for HyperCard, and gcc was generating
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* lousy code, so I've hand-coded and hand-scheduled this for the
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* Pentium. This should do the same thing as the C code below.
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*/
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asm ("movl %0,%2\n\t"
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"movl %0,%1\n\t"
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"sall $5,%2\n\t"
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"shrl $14,%1\n\t"
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"addl %0,%2\n\t"
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"xorl %2,%1\n\t"
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"xorw (%4,%5,2),%w0\n\t"
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"xorl %1,%0"
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: "=r" (sum), "=&r" (tmp1), "=&r" (tmp2)
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: "0" (sum), "r" (code), "r" (n)
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: "cc");
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#else /* !__GNUC__ || !i386 */
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sum = (sum >> 14) ^ (sum * 33) ^ code[n];
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#endif /* !__GNUC__ || !i386 */
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}
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return sum;
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}
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#endif /* INLINE_CHECKSUM */
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#endif /* CHECKSUM_BLOCKS */
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#endif /* Not _checksum_h_ */
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