mul48.c

msp430F437三相电表DEMO(编译器 IAR 3.42A）

//--------------------------------------------------------------------------
//
//  Software for MSP430 based e-meters.
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//
//  File: mul48.c
//
//  Steve Underwood <[e-mail]>
//  Texas Instruments Hong Kong Ltd.
//
//  $Id: mul48.c,v 1.2 2003/07/28 10:15:41 XHKJAMES Exp $
//
//--------------------------------------------------------------------------
#include <stdint.h>
#include "emeter-toolkit-custom.h"
#include "emeter-toolkit.h"

//mul48 is a 32x16=>top 32 bits multiply
int32_t mul48(int32_t x, int16_t y)
{
    register int32_t z;
    register int16_t residue;
#if !(defined(__GNUC__)  &&  defined(__MSP430__))  &&  !defined(__AQCOMPILER__)
    int64_t tmp;
#endif

    z = x & 0xFFFF;
    z *= y;
    residue = z & 0xFFFF;
    z >>= 16;
    x >>= 16;
    x *= y;
    z += x;
#if defined(__GNUC__)  &&  defined(__MSP430__)
    __asm__ (
        " rla %[residue] \n"
        " rlc %A[z] \n"
        " rlc %B[z] \n"
        : [z] "+r"(z)
        : [residue] "r"(residue));
#elif defined(__AQCOMPILER__)
    /$
        rla @residue
        rlc @z.1
        rlc @z.0
    $/
#else
    tmp = z;
    tmp <<= 1;
    if ((residue & 0x8000))
        tmp |= 1;
    z = tmp;
#endif
    return z;
}