iverilog/ivtest/ivltests/sbyte_test.v

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// Ten basic tests in here:
// 1. byte must be initialised before any initial or always block
// 2. assignments to (signed) bytes with random numbers
// 3. assignments to (signed) bytes with random values including X and Z
// 4. converting unsigned integers to signed bytes
// 5. converting signed integers to signed bytes
// 6. converting integers including X and Z states to signed bytes
// 7. trying signed sums (procedural, function, task and module)
// 8. trying signed mults (procedural, function and task)
// 9. trying relational operators
// 10. smaller signed numbers to signed bytes (sign extension)
module ms_add (input byte signed a, b, output byte signed sc, ss);
assign sc = a + b;
always @(a, b) ss = a + b;
endmodule
module main;
parameter N_REPS = 500; // repetition with random numbers
parameter XZ_REPS = 500; // repetition with 'x 'z values
parameter MAX = 'h7f;
parameter LEN = 8;
// variables used as golden references
reg signed [LEN-1:0] ar; // holds numbers
reg signed [LEN-1:0] ar_xz; // holds 'x and/or 'z in random positions
reg signed [LEN-1:0] ar_expected;
integer unsigned ui;
integer signed si;
reg signed [LEN/2-1:0] slice;
// types to be tested
byte signed bu; // holds numbers
byte signed bu_xz; // 'x and 'z are attempted on this
byte signed bresult; // hold results from sums and mults
byte signed mcaresult; // this is permanently wired to a module
byte signed mabresult; // this is permanently wired to a module
integer i;
// continuous assigments
// type LHS type RHS
// --------- ---------
// byte 4-value logic
assign bu = ar;
assign bu_xz = ar_xz;
// module instantiation
ms_add duv (.a(bu), .b(bu_xz), .sc(mcaresult), .ss(mabresult) );
// all test
initial begin
// time 0 checkings (Section 6.4 of IEEE 1850 LRM)
if (bu !== 8'b0 || bu_xz != 8'b0 || bresult !== 8'b0)
begin
$display ("FAILED - time zero initialisation incorrect: %b %b", bu, bu_xz);
$finish;
end
// driving byte type with signed random numbers from a variable
for (i = 0; i< N_REPS; i = i+1)
begin
#1;
ar = $random % MAX;
#1;
if (bu !== ar)
begin
$display ("FAILED - incorrect assigment to byte: %b", bu);
$finish;
end
end
# 1;
// attempting to drive variables having 'x 'z values into type unsigned bytes
// 'x 'z injections (Section 4.3.2 of IEEE 1850 LRM)
for (i = 0; i< XZ_REPS; i = i+1)
begin
#1;
ar = $random % MAX;
ar_xz = xz_inject (ar);
ar_expected = xz_expected (ar_xz);
#1;
if (bu_xz !== ar_expected) // 'x -> '0, 'z -> '0
begin
$display ("FAILED - incorrect assigment to byte (when 'x 'z): %b", bu);
$finish;
end
end
// converting unsigned integers to signed bytes
// truncation expected (Section 4.3.2 of IEEE 1850 LRM)
for (i = 0; i< N_REPS; i = i+1)
begin
#1;
ui = {$random} % 2*(MAX+1); // full range as unsigned
#1;
force bu = ui;
#1;
if (bu !== ui[LEN-1:0])
begin
$display ("FAILED - incorrect truncation from unsigned integer to byte: %b", bu);
$finish;
end
end
release bu;
// converting signed integers to signed bytes
// truncation expected (Section 4.3.2 of IEEE 1850 LRM)
for (i = 0; i< N_REPS; i = i+1)
begin
#1;
si = $random % MAX;
#1;
force bu = si;
#1;
if (bu !== si[LEN-1:0])
begin
$display ("FAILED - incorrect truncation from signed integer to byte: %b mismatchs %b", bu, si[LEN-1:0]);
$finish;
end
end
release bu;
// converting signed integers having 'x 'z values into type signed bytes
// 'x 'z injections (Section 4.3.2 of IEEE 1850 LRM)
// truncation and coercion to zero expected
for (i = 0; i< XZ_REPS; i = i+1)
begin
#1;
si = $random;
ar_xz = xz_inject (si[LEN-1:0]);
si = {si[31:LEN], ar_xz};
ar_expected = xz_expected (ar_xz);
#1;
force bu_xz = si;
#1;
if (bu_xz !== ar_expected) // 'x -> '0, 'z -> '0
begin
$display ("FAILED - incorrect conversion from integer (with 'x 'z) to byte: %b mismatchs %b", bu_xz, ar_expected);
$finish;
end
end
release bu_xz;
// trying signed sums
for (i = 0; i< N_REPS; i = i+1)
begin
#1;
ar = $random % MAX;
ar_xz = $random % MAX;
#1;
bresult = bu + bu_xz;
#1;
if ( bresult !== s_sum(ar, ar_xz) )
begin
$display ("FAILED - incorrect addition of signed bytes: %0d mismatchs %0d", bresult, s_sum(ar, ar_xz));
$finish;
end
// invoking byte sum function
if ( fs_sum (bu, bu_xz) !== s_sum(ar, ar_xz) )
begin
$display ("FAILED - incorrect addition of signed bytes in function");
$finish;
end
// invoking byte sum task
ts_sum (bu, bu_xz, bresult);
if ( bresult !== s_sum(ar, ar_xz) )
begin
$display ("FAILED - incorrect addition of signed bytes in task: %0d mismatchs %0d", bresult, s_sum(ar, ar_xz));
$finish;
end
// checking byte sum from module
if ( mcaresult !== s_sum(ar, ar_xz) || mabresult !== s_sum(ar, ar_xz))
begin
$display ("FAILED - incorrect addition of signed bytes from module");
$finish;
end
end
// trying signed mults, forcing truncation
for (i = 0; i< N_REPS; i = i+1)
begin
#1;
ar = ($random % MAX) << LEN/2;
ar_xz = ($random % MAX) << (LEN/2 - 1);
#1;
bresult = bu * bu_xz;
#1;
if ( bresult !== s_mul(ar, ar_xz) )
begin
$display ("FAILED - incorrect product of signed bytes: %0d mismatchs %0d", bresult, s_mul(ar, ar_xz));
$finish;
end
// invoking byte mult function
if ( fs_mul (bu, bu_xz) !== s_mul(ar, ar_xz) )
begin
$display ("FAILED - incorrect product of signed bytes in function");
$finish;
end
// invoking byte mult task
ts_mul (bu, bu_xz, bresult);
if ( bresult !== s_mul(ar, ar_xz) )
begin
$display ("FAILED - incorrect product of signed bytes in task: %0d mismatchs %0d", bresult, s_mul(ar, ar_xz));
$finish;
end
end
// trying relational operators
for (i = 0; i< N_REPS; i = i+1)
begin
#1;
ar = $random % MAX;
ar_xz = $random % MAX;
#1;
if ( (bu < bu_xz ) !== (ar < ar_xz) )
begin
$display ("FAILED - incorrect 'less than' on signed bytes");
$finish;
end
if ( (bu <= bu_xz ) !== (ar <= ar_xz) )
begin
$display ("FAILED - incorrect 'less than or equal' on signed bytes");
$finish;
end
if ( (bu > bu_xz ) !== (ar > ar_xz) )
begin
$display ("FAILED - incorrect 'greater than' on signed bytes");
$finish;
end
if ( (bu >= bu_xz ) !== (ar >= ar_xz) )
begin
$display ("FAILED - incorrect 'greater than or equal' than on signed bytes");
$finish;
end
if ( (bu == bu_xz ) !== (ar == ar_xz) )
begin
$display ("FAILED - incorrect 'equal to' on signed bytes");
$finish;
end
if ( (bu != bu_xz ) !== (ar != ar_xz) )
begin
$display ("FAILED - incorrect 'not equal to' on signed bytes");
$finish;
end
end
// signed small number to signed byte
for (i = 0; i < (1<<LEN/2); i = i+1)
begin
#1;
slice = $random % 'h7;
force bu = slice;
ar = slice;
#1;
if (bu !== ar)
begin
$display ("FAILED - incorrect signed extend to signed bytes");
$finish;
end
end
release bu;
# 1;
$display("PASSED");
end
// this returns X and Z states into bit random positions for a value
function [LEN-1:0] xz_inject (input signed [LEN-1:0] value);
integer i, temp;
begin
temp = {$random} % 2*(MAX+1); // possible 1 in any position
for (i=0; i<LEN; i=i+1)
begin
if (temp[i] == 1'b1)
begin
temp = $random % MAX;
if (temp <= 0)
value[i] = 1'bx; // 'x noise
else
value[i] = 1'bz; // 'z noise
end
end
xz_inject = value;
end
endfunction
// this function returns bit positions with either X or Z to 0 for an input value
function [LEN-1:0] xz_expected (input signed [LEN-1:0] value_xz);
integer i;
begin
for (i=0; i<LEN; i=i+1)
begin
if (value_xz[i] === 1'bx || value_xz[i] === 1'bz )
value_xz[i] = 1'b0; // forced to zero
end
xz_expected = value_xz;
end
endfunction
// signed 4-value sum
function signed [LEN-1:0] s_sum (input signed [LEN-1:0] a, b);
s_sum = a + b;
endfunction
// signed byte sum as function
function byte signed fs_sum (input byte signed a, b);
fs_sum = a + b;
endfunction
// signed byte sum as task
task ts_sum (input byte signed a, b, output byte signed c);
c = a + b;
endtask
// signed 4-value mults
function signed [LEN-1:0] s_mul (input signed [LEN-1:0] a, b);
s_mul = a * b;
endfunction
// signed byte mults
function byte signed fs_mul (input byte signed a, b);
fs_mul = a * b;
endfunction
// signed byte mult as task
task ts_mul (input byte signed a, b, output byte signed c);
c = a * b;
endtask
endmodule