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B18 Coverage #111

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Merged
coreyqh merged 7 commits into from
May 8, 2026
Merged

B18 Coverage #111

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e696c47
Initial B18 Coverage
fourth-bit May 2, 2026
6cb8959
Actually track pre addition information for B18
fourth-bit May 6, 2026
ed5772e
Correct no underflow coverpoint
fourth-bit May 6, 2026
e4d453c
Correct Coverage for B5 Cases
fourth-bit May 6, 2026
00bb2b0
Redo Case i of B18 to correctly handle all fma Pre Addition Values
fourth-bit May 6, 2026
0e948a8
Fix up the B4 cases of B18 coverage
fourth-bit May 6, 2026
04f00ed
Actually enable all of the covergroups
fourth-bit May 7, 2026
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2 changes: 1 addition & 1 deletion config.svh
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Original file line number Diff line number Diff line change
Expand Up @@ -33,7 +33,7 @@
// `define COVER_B15
`define COVER_B16
// `define COVER_B17
// `define COVER_B18
`define COVER_B18
`define COVER_B19
// `define COVER_B20
`define COVER_B21
Expand Down
73 changes: 63 additions & 10 deletions coverage/coverfloat_pkg.sv
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Original file line number Diff line number Diff line change
Expand Up @@ -204,6 +204,13 @@ package coverfloat_pkg;
logic [111:0] one;
} max_int_struct;

// Helpers for finding the first fractional digit in FMA_PreAddition
parameter int F32_FMA_PRE_ADDITION_NF = 2 * F32_M_BITS;
parameter int F64_FMA_PRE_ADDITION_NF = 2 * F64_M_BITS;
parameter int F128_FMA_PRE_ADDITION_NF = 2 * F128_M_BITS;
parameter int F16_FMA_PRE_ADDITION_NF = 2 * F16_M_BITS;
parameter int BF16_FMA_PRE_ADDITION_NF = 2 * BF16_M_BITS;

// Some Constants For B28
// This value seems like an odd choice ... because it is a trivial task for rfi,
// it seems like the intention should be 1.1111 * 2^(precision-2) as that is the maximum value
Expand Down Expand Up @@ -441,12 +448,15 @@ package coverfloat_pkg;
logic [F16_E_BITS-1:0] exp_a = a[14:10];
logic [F16_E_BITS-1:0] exp_b = b[14:10];

logic [F16_M_BITS-1:0] sig_a = a[F16_M_UPPER:0];
logic [F16_M_BITS-1:0] sig_b = b[F16_M_UPPER:0];

E_a = (exp_a == 0) ?
(1 - F16_EXP_BIAS) :
(0 - F16_EXP_BIAS - count_leading_zeros(sig_a, F16_M_BITS)) :
(int'(exp_a) - F16_EXP_BIAS);

E_b = (exp_b == 0) ?
(1 - F16_EXP_BIAS) :
(0 - F16_EXP_BIAS - count_leading_zeros(sig_b, F16_M_BITS)) :
(int'(exp_b) - F16_EXP_BIAS);

bias = F16_EXP_BIAS;
Expand All @@ -460,12 +470,15 @@ package coverfloat_pkg;
logic [BF16_E_BITS-1:0] exp_a = a[14:7];
logic [BF16_E_BITS-1:0] exp_b = b[14:7];

logic [BF16_M_BITS-1:0] sig_a = a[BF16_M_UPPER:0];
logic [BF16_M_BITS-1:0] sig_b = b[BF16_M_UPPER:0];

E_a = (exp_a == 0) ?
(1 - BF16_EXP_BIAS) :
(0 - BF16_EXP_BIAS - count_leading_zeros(sig_a, BF16_M_BITS)) :
(int'(exp_a) - BF16_EXP_BIAS);

E_b = (exp_b == 0) ?
(1 - BF16_EXP_BIAS) :
(0 - BF16_EXP_BIAS - count_leading_zeros(sig_b, BF16_M_BITS)) :
(int'(exp_b) - BF16_EXP_BIAS);

bias = BF16_EXP_BIAS;
Expand All @@ -479,12 +492,15 @@ package coverfloat_pkg;
logic [F32_E_BITS-1:0] exp_a = a[30:23];
logic [F32_E_BITS-1:0] exp_b = b[30:23];

logic [F32_M_BITS-1:0] sig_a = a[F32_M_UPPER:0];
logic [F32_M_BITS-1:0] sig_b = b[F32_M_UPPER:0];

E_a = (exp_a == 0) ?
(1 - F32_EXP_BIAS) :
(0 - F32_EXP_BIAS - count_leading_zeros(sig_a, F32_M_BITS)) :
(int'(exp_a) - F32_EXP_BIAS);

E_b = (exp_b == 0) ?
(1 - F32_EXP_BIAS) :
(0 - F32_EXP_BIAS - count_leading_zeros(sig_b, F32_M_BITS)) :
(int'(exp_b) - F32_EXP_BIAS);

bias = F32_EXP_BIAS;
Expand All @@ -498,12 +514,15 @@ package coverfloat_pkg;
logic [F64_E_BITS-1:0] exp_a = a[62:52];
logic [F64_E_BITS-1:0] exp_b = b[62:52];

logic [F64_M_BITS-1:0] sig_a = a[F64_M_UPPER:0];
logic [F64_M_BITS-1:0] sig_b = b[F64_M_UPPER:0];

E_a = (exp_a == 0) ?
(1 - F64_EXP_BIAS) :
(0 - F64_EXP_BIAS - count_leading_zeros(sig_a, F64_M_BITS)) :
(int'(exp_a) - F64_EXP_BIAS);

E_b = (exp_b == 0) ?
(1 - F64_EXP_BIAS) :
(0 - F64_EXP_BIAS - count_leading_zeros(sig_b, F64_M_BITS)) :
(int'(exp_b) - F64_EXP_BIAS);

bias = F64_EXP_BIAS;
Expand All @@ -517,12 +536,15 @@ package coverfloat_pkg;
logic [F128_E_BITS-1:0] exp_a = a[126:112];
logic [F128_E_BITS-1:0] exp_b = b[126:112];

logic [F128_M_BITS-1:0] sig_a = a[F128_M_UPPER:0];
logic [F128_M_BITS-1:0] sig_b = b[F128_M_UPPER:0];

E_a = (exp_a == 0) ?
(1 - F128_EXP_BIAS) :
(0 - F128_EXP_BIAS - count_leading_zeros(sig_a, F128_M_BITS)) :
(int'(exp_a) - F128_EXP_BIAS);

E_b = (exp_b == 0) ?
(1 - F128_EXP_BIAS) :
(0 - F128_EXP_BIAS - count_leading_zeros(sig_b, F128_M_BITS)) :
(int'(exp_b) - F128_EXP_BIAS);

bias = F128_EXP_BIAS;
Expand All @@ -539,6 +561,37 @@ package coverfloat_pkg;

endfunction

function automatic int get_effective_product_exponent(
input logic[127:0] a,
input logic[127:0] b,
input logic[255:0] pre_addition,
input logic [7:0] fmt
);
int shift_one;

case (fmt)
FMT_BF16: begin
shift_one = pre_addition[BF16_FMA_PRE_ADDITION_NF+1];
end
FMT_HALF: begin
shift_one = pre_addition[F16_FMA_PRE_ADDITION_NF+1];
end
FMT_SINGLE: begin
shift_one = pre_addition[F32_FMA_PRE_ADDITION_NF+1];
end
FMT_DOUBLE: begin
shift_one = pre_addition[F64_FMA_PRE_ADDITION_NF+1];
end
FMT_QUAD: begin
shift_one = pre_addition[F128_FMA_PRE_ADDITION_NF+1];
end
endcase

return get_product_exponent(a, b, fmt) + shift_one;

endfunction


function automatic int get_unbiased_exponent(
input logic [127:0] input_val,
input logic [7:0] fmt
Expand Down
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