Bitstream structure

The raw XPLA3 bitstream is a three-dimensional array of bits. The bitstream is arranged into:

• fb_rows * 52 + 2 rows
• 2 planes
• bs_cols columns

The fb_rows and bs_cols variables are per-device and can be obtained from the database.

The bitstream is roughly divided into areas as follows:

• the last row is used to store the UES (user electronic signature)
• the second to last row is used to store the READ_PROT and ISP_DISABLE bits, which should generally be programmed last in the sequence
• all other rows are used to store (mostly) per-FB data, with 52 bitstream rows per FB row
  • each FB column has three ranges of columns, the start of each range is stored in the database:
    • IMUX bits (includes per-FB input multiplexers and the per-column ZIA_GCLK*_ENABLE bits)
    • PT bits (includes product term bits and PLA sum term bits)
    • MC bits (includes per-MC config bits and misc per-FB config bits; also includes global bits configuring UCT muxes)

JED structure

XPLA3 bitstreams are commonly stored in JED files. Bits in JED files are stored in a logical order completely unrelated to the physical structure of a bitstream. The order of bits in a JED file is as follows:

• per-FB bits, for every FB i in order:
  • IMUX bits, for every j < 40:
    • every bit of FB[i].IM[j].MUX in order
  • for every product term j < 48, in order:
    • for every FB input k < 40, in order:
      • FB[i].PT[i].IM[k].P
      • FB[i].PT[i].IM[k].N
    • for every feedback term k < 8, in order:
      • FB[i].PT[i].FBN[k]
  • for every product term j < 48, in order:
    • for every macrocell k < 16, in order:
      • FB[i].MC[k].SUM.PT[j]
  • misc per-FB bits, in order given below
  • for every macrocell with an IOB, in order (which macrocells have a IOB can be checked in the database io_mcs field):
    • misc per-MC bits, in order given below
  • for every macrocell without an IOB, in order:
    • misc per-MC bits, in order given below
• all global bits, in order given in the per-device database

Note that the UES bits and read protection bit are not included in the JED file, and must be provided out of band.

Fuses — IMUX bits

The size of every FB[i].IM[j].MUX fuse set in the device is the same, and is given by the database imux_width field. The position of bit k of FB[i].IM[j].MUX in the fuse array can be computed as follows:

• row is:
  • if j < 20: fb_row(i) * 52 + 2 + j
  • if j >= 20: fb_row(i) * 52 + 2 + j + 8
• plane is: (i & 1) ^ 1
• column is fb_cols[fb_col(i)].imux_col + imux_width - 1 - k

Fuses — product and sum terms

The position of FB[i].PT[j].IM[k].P and FB[i].PT[j].IM[k].N can be computed as follows:

• row is:
  • if k < 20: fb_row(i) * 52 + 2 + k
  • if k >= 20: fb_row(i) * 52 + 2 + k + 8
• plane is 0 for .P bit, 1 for .N bit
• column is:
  • if i is even: fb_cols[fb_col(i)].pt_col + j
  • if i is odd: fb_cols[fb_col(i)].pt_col + 95 - j

The position of FB[i].PT[j].FBN[k] can be computed as follows:

• row is fb_row(i) * 52 + dr, where dr is given in the table below
• plane is given in the table below
• column is:
  • if i is even: fb_cols[fb_col(i)].pt_col + j
  • if i is odd: fb_cols[fb_col(i)].pt_col + 95 - j

The position of FB[i].MC[j].SUM.PT[k] can be computed as follows:

• row is fb_row(i) * 52 + 22 + (j // 2)
• plane is 1 - (j % 2)
• column is:
  • if i is even: fb_cols[fb_col(i)].pt_col + k
  • if i is odd: fb_cols[fb_col(i)].pt_col + 95 - k

Fuses — macrocells

The per-MC bits are listed in the table below. The per-MC coordinates should be translated to global coordinates as follows:

• row is: if mc < 8: fb_row(fb) * 52 + mc * 3 + table_row if mc >= 8: fb_row(fb) * 52 + 4 + mc * 3 + table_row
• plane is: table_plane
• column is:
  • if fb is even: fb_cols[fb_col(fb)].mc_col + table_column
  • if fb is odd: fb_cols[fb_col(fb)].mc_col + 9 - table_column

JED mapping — macrocells with IOB

JED mapping — macrocells without IOB

Fuses — FBs

The per-FB bits are listed in the table below. The per-FB coordinates should be translated to global coordinates as follows:

• row is: fb_row(fb) * 52 + 24 + table_row
• plane is: table_plane
• column is:
  • if fb is even: fb_cols[fb_col(fb)].mc_col + table_column
  • if fb is odd: fb_cols[fb_col(fb)].mc_col + 9 - table_column

JED mapping

Fuses — global bits

The global bits are given by their raw position in the per-device database.