#include "gmp.h"

// This is an AltiVec-enhanced mpn_lshift() routine
// To compile with gcc, use the -faltivec flag in addition to any other flags
mp_limb_t mpn_lshift(mp_limb_t *rp, const mp_limb_t *sp, mp_size_t n, unsigned int count)
{
    int i, lshift_int, rshift_int;
    
    lshift_int = count;
    rshift_int = 32 - count;
    
    if(n > 3)
    {
        vector unsigned int lshift, rshift, zero, temp, temp2, carry_shift;
        vector unsigned int *a = (vector unsigned int*)sp, *result = (vector unsigned int*)rp;
    
        zero = (vector unsigned int)(0);
        temp = vec_lde(0, &count);
        temp2 = vec_perm(temp, zero, vec_lvsl(0, &count));
        lshift = vec_splat(temp2, 0);
        rshift = vec_sub((vector unsigned int)(32), lshift);
        carry_shift = zero;
        
        for(i = 0; i < (n >> 2); i++)
        {
            temp = vec_sl(a[i], lshift);
            temp2 = vec_sr(a[i], rshift);
            result[i] = vec_or(temp, vec_sld(carry_shift, temp2, 12));
            carry_shift = temp2;
        }
        for(i = ((n >> 2) << 2); i < n; i++)
        {
            rp[i] = (sp[i] << lshift_int) | (sp[i - 1] >> rshift_int);
        }
    }else{	// n <= 3
        rp[0] = sp[0] << lshift_int;
        for(i = 1; i < n; i++)
        {
            rp[i] = (sp[i] << lshift_int) | (sp[i - 1] >> rshift_int);
        }
    }
    
    return (sp[n - 1] >> (32 - count));
}