non-x86 support: Only use SSE2 when supported
Add generic version of viterbi decoder that does not utilize x86 intrinsics to provide support for other architectures such as ARM.
This commit is contained in:
Stephen Wolfe
+256
-2
@@ -80,7 +80,6 @@
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} \
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}
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using namespace gr::ieee802_11;
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@@ -91,6 +90,7 @@ viterbi_decoder::viterbi_decoder() :
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viterbi_decoder::~viterbi_decoder() {
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}
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#ifdef IEEE80211_MSSE2
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void
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viterbi_decoder::viterbi_butterfly2_sse2(unsigned char *symbols,
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__m128i *mm0, __m128i *mm1, __m128i *pp0, __m128i *pp1) {
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@@ -197,23 +197,236 @@ viterbi_decoder::viterbi_butterfly2_sse2(unsigned char *symbols,
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path1[2*i+1] = _mm_unpackhi_epi8(tmp0, tmp1);
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}
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}
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#else
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void
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viterbi_decoder::viterbi_butterfly2_generic(unsigned char *symbols,
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unsigned char *mm0, unsigned char *mm1, unsigned char *pp0,
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unsigned char *pp1)
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{
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int i, j, k;
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unsigned char *metric0, *metric1;
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unsigned char *path0, *path1;
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metric0 = mm0;
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path0 = pp0;
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metric1 = mm1;
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path1 = pp1;
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// Operate on 4 symbols (2 bits) at a time
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unsigned char m0[16], m1[16], m2[16], m3[16], decision0[16], decision1[16], survivor0[16], survivor1[16];
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unsigned char metsv[16], metsvm[16];
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unsigned char shift0[16], shift1[16];
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unsigned char tmp0[16], tmp1[16];
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unsigned char sym0v[16], sym1v[16];
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unsigned short simd_epi16;
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for (j = 0; j < 16; j++) {
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sym0v[j] = symbols[0];
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sym1v[j] = symbols[1];
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}
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for (i = 0; i < 2; i++) {
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if (symbols[0] == 2) {
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for (j = 0; j < 16; j++) {
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metsvm[j] = d_branchtab27_generic[1].c[(i*16) + j] ^ sym1v[j];
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metsv[j] = 1 - metsvm[j];
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}
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}
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else if (symbols[1] == 2) {
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for (j = 0; j < 16; j++) {
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metsvm[j] = d_branchtab27_generic[0].c[(i*16) + j] ^ sym0v[j];
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metsv[j] = 1 - metsvm[j];
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}
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}
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else {
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for (j = 0; j < 16; j++) {
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metsvm[j] = (d_branchtab27_generic[0].c[(i*16) + j] ^ sym0v[j]) + (d_branchtab27_generic[1].c[(i*16) + j] ^ sym1v[j]);
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metsv[j] = 2 - metsvm[j];
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}
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}
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for (j = 0; j < 16; j++) {
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m0[j] = metric0[(i*16) + j] + metsv[j];
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m1[j] = metric0[((i+2)*16) + j] + metsvm[j];
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m2[j] = metric0[(i*16) + j] + metsvm[j];
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m3[j] = metric0[((i+2)*16) + j] + metsv[j];
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}
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for (j = 0; j < 16; j++) {
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decision0[j] = ((m0[j] - m1[j]) > 0) ? 0xff : 0x0;
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decision1[j] = ((m2[j] - m3[j]) > 0) ? 0xff : 0x0;
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survivor0[j] = (decision0[j] & m0[j]) | ((~decision0[j]) & m1[j]);
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survivor1[j] = (decision1[j] & m2[j]) | ((~decision1[j]) & m3[j]);
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}
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for (j = 0; j < 16; j += 2) {
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simd_epi16 = path0[(i*16) + j];
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simd_epi16 |= path0[(i*16) + (j+1)] << 8;
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simd_epi16 <<= 1;
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shift0[j] = simd_epi16;
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shift0[j+1] = simd_epi16 >> 8;
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simd_epi16 = path0[((i+2)*16) + j];
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simd_epi16 |= path0[((i+2)*16) + (j+1)] << 8;
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simd_epi16 <<= 1;
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shift1[j] = simd_epi16;
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shift1[j+1] = simd_epi16 >> 8;
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}
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for (j = 0; j < 16; j++) {
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shift1[j] = shift1[j] + 1;
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}
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for (j = 0, k = 0; j < 16; j += 2, k++) {
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metric1[(2*i*16) + j] = survivor0[k];
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metric1[(2*i*16) + (j+1)] = survivor1[k];
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}
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for (j = 0; j < 16; j++) {
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tmp0[j] = (decision0[j] & shift0[j]) | ((~decision0[j]) & shift1[j]);
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}
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for (j = 0, k = 8; j < 16; j += 2, k++) {
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metric1[((2*i+1)*16) + j] = survivor0[k];
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metric1[((2*i+1)*16) + (j+1)] = survivor1[k];
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}
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for (j = 0; j < 16; j++) {
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tmp1[j] = (decision1[j] & shift0[j]) | ((~decision1[j]) & shift1[j]);
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}
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for (j = 0, k = 0; j < 16; j += 2, k++) {
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path1[(2*i*16) + j] = tmp0[k];
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path1[(2*i*16) + (j+1)] = tmp1[k];
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}
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for (j = 0, k = 8; j < 16; j += 2, k++) {
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path1[((2*i+1)*16) + j] = tmp0[k];
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path1[((2*i+1)*16) + (j+1)] = tmp1[k];
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}
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}
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metric0 = mm1;
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path0 = pp1;
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metric1 = mm0;
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path1 = pp0;
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for (j = 0; j < 16; j++) {
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sym0v[j] = symbols[2];
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sym1v[j] = symbols[3];
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}
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for (i = 0; i < 2; i++) {
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if (symbols[2] == 2) {
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for (j = 0; j < 16; j++) {
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metsvm[j] = d_branchtab27_generic[1].c[(i*16) + j] ^ sym1v[j];
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metsv[j] = 1 - metsvm[j];
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}
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}
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else if (symbols[3] == 2) {
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for (j = 0; j < 16; j++) {
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metsvm[j] = d_branchtab27_generic[0].c[(i*16) + j] ^ sym0v[j];
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metsv[j] = 1 - metsvm[j];
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}
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}
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else {
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for (j = 0; j < 16; j++) {
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metsvm[j] = (d_branchtab27_generic[0].c[(i*16) + j] ^ sym0v[j]) + (d_branchtab27_generic[1].c[(i*16) + j] ^ sym1v[j]);
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metsv[j] = 2 - metsvm[j];
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}
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}
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for (j = 0; j < 16; j++) {
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m0[j] = metric0[(i*16) + j] + metsv[j];
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m1[j] = metric0[((i+2)*16) + j] + metsvm[j];
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m2[j] = metric0[(i*16) + j] + metsvm[j];
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m3[j] = metric0[((i+2)*16) + j] + metsv[j];
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}
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for (j = 0; j < 16; j++) {
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decision0[j] = ((m0[j] - m1[j]) > 0) ? 0xff : 0x0;
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decision1[j] = ((m2[j] - m3[j]) > 0) ? 0xff : 0x0;
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survivor0[j] = (decision0[j] & m0[j]) | ((~decision0[j]) & m1[j]);
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survivor1[j] = (decision1[j] & m2[j]) | ((~decision1[j]) & m3[j]);
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}
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for (j = 0; j < 16; j += 2) {
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simd_epi16 = path0[(i*16) + j];
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simd_epi16 |= path0[(i*16) + (j+1)] << 8;
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simd_epi16 <<= 1;
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shift0[j] = simd_epi16;
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shift0[j+1] = simd_epi16 >> 8;
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simd_epi16 = path0[((i+2)*16) + j];
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simd_epi16 |= path0[((i+2)*16) + (j+1)] << 8;
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simd_epi16 <<= 1;
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shift1[j] = simd_epi16;
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shift1[j+1] = simd_epi16 >> 8;
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}
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for (j = 0; j < 16; j++) {
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shift1[j] = shift1[j] + 1;
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}
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for (j = 0, k = 0; j < 16; j += 2, k++) {
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metric1[(2*i*16) + j] = survivor0[k];
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metric1[(2*i*16) + (j+1)] = survivor1[k];
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}
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for (j = 0; j < 16; j++) {
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tmp0[j] = (decision0[j] & shift0[j]) | ((~decision0[j]) & shift1[j]);
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}
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for (j = 0, k = 8; j < 16; j += 2, k++) {
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metric1[((2*i+1)*16) + j] = survivor0[k];
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metric1[((2*i+1)*16) + (j+1)] = survivor1[k];
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}
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for (j = 0; j < 16; j++) {
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tmp1[j] = (decision1[j] & shift0[j]) | ((~decision1[j]) & shift1[j]);
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}
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for (j = 0, k = 0; j < 16; j += 2, k++) {
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path1[(2*i*16) + j] = tmp0[k];
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path1[(2*i*16) + (j+1)] = tmp1[k];
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}
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for (j = 0, k = 8; j < 16; j += 2, k++) {
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path1[((2*i+1)*16) + j] = tmp0[k];
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path1[((2*i+1)*16) + (j+1)] = tmp1[k];
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}
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}
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}
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#endif
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// Find current best path
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#ifdef IEEE80211_MSSE2
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unsigned char
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viterbi_decoder::viterbi_get_output_sse2(__m128i *mm0, __m128i *pp0,
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int ntraceback, unsigned char *outbuf) {
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#else
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unsigned char
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viterbi_decoder::viterbi_get_output_generic(unsigned char *mm0,
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unsigned char *pp0, int ntraceback, unsigned char *outbuf) {
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#endif
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int i;
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int bestmetric, minmetric;
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int beststate = 0;
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int pos = 0;
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#ifndef IEEE80211_MSSE2
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int j;
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#endif
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// circular buffer with the last ntraceback paths
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d_store_pos = (d_store_pos + 1) % ntraceback;
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#ifdef IEEE80211_MSSE2
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for (i = 0; i < 4; i++) {
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_mm_store_si128((__m128i *) &d_mmresult[i*16], mm0[i]);
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_mm_store_si128((__m128i *) &d_ppresult[d_store_pos][i*16], pp0[i]);
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}
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#else
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for (i = 0; i < 4; i++) {
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for (j = 0; j < 16; j++) {
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d_mmresult[(i*16) + j] = mm0[(i*16) + j];
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d_ppresult[d_store_pos][(i*16) + j] = pp0[(i*16) + j];
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}
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}
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#endif
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// Find out the best final state
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bestmetric = d_mmresult[beststate];
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@@ -241,12 +454,21 @@ viterbi_decoder::viterbi_get_output_sse2(__m128i *mm0, __m128i *pp0,
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// Store output byte
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*outbuf = d_ppresult[pos][beststate];
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#ifdef IEEE80211_MSSE2
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// Zero out the path variable
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// and prevent metric overflow
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for (i = 0; i < 4; i++) {
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pp0[i] = _mm_setzero_si128();
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mm0[i] = _mm_sub_epi8(mm0[i], _mm_set1_epi8(minmetric));
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}
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#else
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for (i = 0; i < 4; i++) {
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for (j = 0; j < 16; j++) {
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pp0[(i*16) + j] = 0;
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mm0[(i*16) + j] = mm0[(i*16) + j] - minmetric;
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}
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}
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#endif
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return bestmetric;
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}
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@@ -303,12 +525,21 @@ viterbi_decoder::decode(ofdm_param *ofdm, frame_param *frame, uint8_t *in) {
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while(n_decoded < d_frame->n_data_bits) {
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if ((in_count % 4) == 0) { //0 or 3
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#ifdef IEEE80211_MSSE2
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viterbi_butterfly2_sse2(&depunctured[in_count & 0xfffffffc], d_metric0, d_metric1, d_path0, d_path1);
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#else
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viterbi_butterfly2_generic(&depunctured[in_count & 0xfffffffc], d_metric0_generic, d_metric1_generic,
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d_path0_generic, d_path1_generic);
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#endif
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if ((in_count > 0) && (in_count % 16) == 8) { // 8 or 11
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unsigned char c;
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#ifdef IEEE80211_MSSE2
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viterbi_get_output_sse2(d_metric0, d_path0, d_ntraceback, &c);
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#else
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viterbi_get_output_generic(d_metric0_generic, d_path0_generic, d_ntraceback, &c);
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#endif
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if (out_count >= d_ntraceback) {
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for (int i= 0; i < 8; i++) {
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@@ -328,7 +559,11 @@ viterbi_decoder::decode(ofdm_param *ofdm, frame_param *frame, uint8_t *in) {
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void
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viterbi_decoder::reset() {
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#ifdef IEEE80211_MSSE2
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viterbi_chunks_init_sse2();
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#else
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viterbi_chunks_init_generic();
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#endif
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switch(d_ofdm->encoding) {
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case BPSK_1_2:
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@@ -354,10 +589,17 @@ viterbi_decoder::reset() {
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}
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}
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void // Initialize starting metrics to prefer 0 state
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// Initialize starting metrics to prefer 0 state
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#ifdef IEEE80211_MSSE2
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void
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viterbi_decoder::viterbi_chunks_init_sse2() {
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#else
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void
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viterbi_decoder::viterbi_chunks_init_generic() {
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#endif
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int i, j;
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#ifdef IEEE80211_MSSE2
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for (i = 0; i < 4; i++) {
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d_metric0[i] = _mm_setzero_si128();
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d_path0[i] = _mm_setzero_si128();
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@@ -368,6 +610,18 @@ viterbi_decoder::viterbi_chunks_init_sse2() {
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d_branchtab27_sse2[0].c[i] = (polys[0] < 0) ^ PARTAB[(2*i) & abs(polys[0])] ? 1 : 0;
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d_branchtab27_sse2[1].c[i] = (polys[1] < 0) ^ PARTAB[(2*i) & abs(polys[1])] ? 1 : 0;
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}
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#else
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for (i = 0; i < 4; i++) {
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d_metric0_generic[i] = 0;
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d_path0_generic[i] = 0;
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}
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int polys[2] = { 0x6d, 0x4f };
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for(i=0; i < 32; i++) {
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d_branchtab27_generic[0].c[i] = (polys[0] < 0) ^ PARTAB[(2*i) & abs(polys[0])] ? 1 : 0;
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d_branchtab27_generic[1].c[i] = (polys[1] < 0) ^ PARTAB[(2*i) & abs(polys[1])] ? 1 : 0;
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}
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#endif
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for (i = 0; i < 64; i++) {
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d_mmresult[i] = 0;
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