Utilities library

Table of Contents

• Utilities
  • Functionality
  • Example use

This library provides functions for data array manipulation.

Utilities

Functionality

• Repack data arrays to new data width, padding before or after
• Flip bits in data words or swap endianess
• Concatenate data array lengthwise or widthwise
• Search for token in data arrays

Other libraries in Utilities are:

• Checksum and CRC
• PRBS
• NRS
• AXI-Stream source
• AXI-Stream sink

More details in nw_util_pkg

Example use

Include the libraries:

library nw_util;
context nw_util.nw_util_context;

Bit-flip (reflect) and swap endianness of data arrays and std_logic_vectors:

array_8bit    := (x"c1", x"67");
array_flipped := f_bitflip(array_8bit); -- array_flipped is now (x"83", x"e6")
v_a           := "1100001111";
v_a_flipped   := f_bitflip(v_a); -- v_a_flipped is now "1111000011"
array_32bit   := (x"11223344", x"abcdef00);
array_swapped := f_swap_endian(array_32bit); -- array_swapped is now (x"44332211",  x"00efcdab")

Concatenate data arrays:

array_8bit   := (x"c1", x"67");
array2_8bit  := (x"55", x"8f", x"42);
array_concat := f_concat(array_8bit, array2_8bit); -- array_concat is now (x"c1", x"67", x"55", x"8f", x"42)

Repack data arrays to new data word width:

array_8bit  := (x"11", x"22", x"33", x"44", x"55", x"66", x"77");
array_32bit := f_repack(array_8bit, 32, C_MSB_FIRST, C_PAD_BEFORE, x"ff"); -- array_32bit is now (x"ff112233", x"44556677")
array_32bit := f_repack(array_8bit, 32, C_LSB_FIRST, C_PAD_BEFORE, x"ff"); -- array_32bit is now (x"332211ff", x"77665544")
array_1bit  := f_repack(array_8bit(0 to 0), 1, C_MSB_FIRST); -- array_1bit is now ("0", "0", "0", "1", "0", "0", "0", "1")
array_3bit  := f_repack(array_1bit, 3, C_LSB_FIRST);         -- array_3bit is now ("000", "001", "010")
array_7bit  := f_repack(f_repack(array_8bit, 1), 7); -- array_7bit is now ("0001000", "1001000", "1000110", "0110100", "0100010", ...)

Reverse data arrays:

array_8bit := (x"c1", x"67", x"42");
array_rev  := f_reverse(array_8bit); -- array_rev is now (x"42", x"67", x"c1")

Stack data arrays to create wider data words:

array_8bit  := (x"11", x"22", x"33", x"44", x"55", x"66", x"77");
array_4bit  := (x"0", x"1", x"2", x"3");
array_12bit := f_stack(array_4bit, array_8bit); -- array_12bit is now (x"011", x"122", x"233", x"344)

See further examples in the test bench nw_util_tb.vhd.