mirror of https://github.com/openXC7/prjxray.git
42 lines
745 B
C++
42 lines
745 B
C++
#include <prjxray/xilinx/xc7series/ecc.h>
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namespace prjxray {
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namespace xilinx {
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namespace xc7series {
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uint32_t icap_ecc(uint32_t idx, uint32_t data, uint32_t ecc) {
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uint32_t val = idx * 32; // bit offset
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if (idx > 0x25) // avoid 0x800
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val += 0x1360;
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else if (idx > 0x6) // avoid 0x400
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val += 0x1340;
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else // avoid lower
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val += 0x1320;
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if (idx == 0x32) // mask ECC
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data &= 0xFFFFE000;
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for (int i = 0; i < 32; i++) {
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if (data & 1)
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ecc ^= val + i;
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data >>= 1;
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}
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if (idx == 0x64) { // last index
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uint32_t v = ecc & 0xFFF;
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v ^= v >> 8;
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v ^= v >> 4;
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v ^= v >> 2;
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v ^= v >> 1;
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ecc ^= (v & 1) << 12; // parity
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}
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return ecc;
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}
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} // namespace xc7series
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} // namespace xilinx
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} // namespace prjxray
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