Linzhi ASICs
Mar 29 · 4 min read

// Random math between two input values
uint32_t Math(uint32_t a, uint32_t b, uint32_t r)
{
switch (r % 11)
{
case 0: return a + b;
case 1: return a * b;
case 2: return mul_hi(a, b);
case 3: return min(a, b);
case 4: return ROTL32(a, b);
case 5: return ROTR32(a, b);
case 6: return a & b;
case 7: return a | b;
case 8: return a ^ b;
case 9: return clz(a) + clz(b);
case 10: return popcount(a) + popcount(b);
}
}
  • 32-bit Add, simple logic, ~300gate for a fast one.
  • 32-bit Multiplier, mature IP, ~20Kgate for a fast one, since multiplier only have ~4/11 activity rate, we can use a two cycle multiplier to half the area, small possibility to increase delay.
  • Rotation operation can easily map to a multiplier, for example I want to calculate ROTL(0x12345678, 8), I can do 0x12345678 * 0x00000100 = 0x0000001234567800, then we just need to OR higher word and lower word together to get 0x34567812. so just cost ~160gate extra logic
  • logic operation, A&B only cost 32 gate, A|B 32 gate, A^B 96 gate, it looks like three different instructions but actually extremely small on silicon (<30um²)
  • clz and popcount are also very small
  • We only need a multiplexer to select output.
  • Total size of Math() is about 0.0015mm² on a TSMC16ULP process.
  • Merge() is similar but even smaller, only shifter, adder, and tiny logic (no multipliers because constant multiply can be mapped into adder).
  • Size of Merge() is roughly ~0.0005mm².

  • 0.55V voltage (typical voltage for TSMC16ULP)
  • generating ~10T Math() + Merge() throughput per second
  • Power estimate roughly 3mW each pipeline, 30W in total.
  • No customized circuit/layout
  • All standard cells, auto placement route
  • Use mature IP only
  • No aggressive overclocking
  • No aggressive under voltage
  • ~8.4K Merge() and ~4.8K Math() per hash
  • pipeline includes 1 Merge() and 1 Math()
  • pipeline is only the logic part, not the memory part
  • the xGB memory are not included
  • we have 10T throughput on single chip asic, divided by 8.4K Merge() per hash, means 1.2GHash




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