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81 lines
1.8 KiB
C
81 lines
1.8 KiB
C
//
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// arch/x86_64/rsp/vrcpsq.c
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//
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// This file is subject to the terms and conditions defined in
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// 'LICENSE', which is part of this source code package.
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//
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#include "common.h"
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#include "common/reciprocal.h"
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#include "rsp/cpu.h"
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#include "rsp/rsp.h"
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#include <string.h>
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__m128i rsp_vrcp_vrsq(struct rsp *rsp, uint32_t iw, int dp,
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unsigned src, unsigned e, unsigned dest, unsigned de) {
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uint32_t dp_input, sp_input;
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int32_t input, result;
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int16_t vt;
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int32_t input_mask, data;
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unsigned shift, idx;
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// Get the element from VT.
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vt = rsp->cp2.regs[src].e[e & 0x7];
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dp_input = ((uint32_t) rsp->cp2.div_in << 16) | (uint16_t) vt;
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sp_input = vt;
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input = (dp) ? dp_input : sp_input;
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input_mask = input >> 31;
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data = input ^ input_mask;
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if (input > -32768)
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data -= input_mask;
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// Handle edge cases.
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if (data == 0)
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result = 0x7fffFFFFU;
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else if (input == -32768)
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result = 0xffff0000U;
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// Main case: compute the reciprocal.
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else {
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// TODO: Clean this up.
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#ifdef _MSC_VER
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unsigned long bsf_index;
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_BitScanReverse(&bsf_index, data);
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shift = 31 - bsf_index;
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#else
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shift = __builtin_clz(data);
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#endif
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// VRSQ
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if (iw & 0x4) {
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idx = (((unsigned long long) data << shift) & 0x7FC00000U) >> 22;
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idx = (idx | 0x200) & 0x3FE | (shift % 2);
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result = rsp_reciprocal_rom[idx];
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result = ((0x10000 | result) << 14) >> ((31 - shift) >> 1);
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}
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// VRCP
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else {
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idx = (((unsigned long long) data << shift) & 0x7FC00000U) >> 22;
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result = rsp_reciprocal_rom[idx];
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result = ((0x10000 | result) << 14) >> (31 - shift);
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}
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result = result ^ input_mask;
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}
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// Write out the results.
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rsp->cp2.div_out = result >> 16;
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rsp->cp2.regs[dest].e[de & 0x7] = result;
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return rsp_vect_load_unshuffled_operand(rsp->cp2.regs[dest].e);
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}
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