sign_ext.h

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#ifndef __WSUTIL_SIGN_EXT_H__
#define __WSUTIL_SIGN_EXT_H__
 
#include <inttypes.h>
 
#include <glib.h>
 
#include <wsutil/ws_assert.h>
 
/* sign extension routines */
 
static inline uint32_t
ws_sign_ext32(uint32_t val, int no_of_bits)
{
    ws_assert (no_of_bits >= 0 && no_of_bits <= 32);
 
    if ((no_of_bits == 0) || (no_of_bits == 32))
        return val;
 
    /*
     * Don't shift signed values left; that's not valid in C99, at
     * least, if the value is negative or if the shift count is
     * the number of bits in the value - 1, and we might get
     * compile-time or run-time complaints about that.
     */
    if (val & (1U << (no_of_bits-1)))
        val |= (0xFFFFFFFFU << no_of_bits);
 
    return val;
}
 
static inline uint64_t
ws_sign_ext64(uint64_t val, int no_of_bits)
{
    ws_assert (no_of_bits >= 0 && no_of_bits <= 64);
 
    if ((no_of_bits == 0) || (no_of_bits == 64))
        return val;
 
    /*
     * Don't shift signed values left; that's not valid in C99, at
     * least, if the value is negative or if the shift count is
     * the number of bits in the value - 1, and we might get
     * compile-time or run-time complaints about that.
     */
    if (val & (UINT64_C(1) << (no_of_bits-1)))
        val |= (UINT64_C(0xFFFFFFFFFFFFFFFF) << no_of_bits);
 
    return val;
}
 
/*
static inline uint64_t
ws_sign_ext64(uint64_t val, int no_of_bits)
{
    int64_t sval = (val << (64 - no_of_bits));
 
    return (uint64_t) (sval >> (64 - no_of_bits));
}
*/
 
#endif /* __WSUTIL_SIGN_EXT_H__ */