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// license:BSD-3-Clause
// copyright-holders:Tyler J. Stachecki,Ryan Holtz
inline rsp_vec_t vec_vmadl_vmudl(uint32_t iw, rsp_vec_t vs, rsp_vec_t vt, rsp_vec_t zero, rsp_vec_t *acc_lo, rsp_vec_t *acc_md, rsp_vec_t *acc_hi)
{
rsp_vec_t hi = _mm_mulhi_epu16(vs, vt);
if (iw & 0x8) // VMADL
{
// Tricky part: start accumulating everything.
// Get/keep the carry as we'll add it in later.
rsp_vec_t overflow_mask = _mm_adds_epu16(*acc_lo, hi);
*acc_lo = _mm_add_epi16(*acc_lo, hi);
overflow_mask = _mm_cmpeq_epi16(*acc_lo, overflow_mask);
overflow_mask = _mm_cmpeq_epi16(overflow_mask, zero);
hi = _mm_sub_epi16(zero, overflow_mask);
// Check for overflow of the upper sum.
//
// TODO: Since hi can only be {0,1}, we should
// be able to generalize this for performance.
overflow_mask = _mm_adds_epu16(*acc_md, hi);
*acc_md = _mm_add_epi16(*acc_md, hi);
overflow_mask = _mm_cmpeq_epi16(*acc_md, overflow_mask);
overflow_mask = _mm_cmpeq_epi16(overflow_mask, zero);
// Finish up the accumulation of the... accumulator.
// Since the product was unsigned, only worry about
// positive overflow (i.e.: borrowing not possible).
*acc_hi = _mm_sub_epi16(*acc_hi, overflow_mask);
return uclamp_acc(*acc_lo, *acc_md, *acc_hi, zero);
}
else // VMUDL
{
*acc_lo = hi;
*acc_md = zero;
*acc_hi = zero;
return hi;
}
}
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