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2b4ae64 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 | `timescale 1ns/1ps
module tb_fp16_adder;
reg [15:0] a, b;
wire [15:0] result;
integer pass_count = 0;
integer fail_count = 0;
fp16_adder dut (.a(a), .b(b), .result(result));
// FP16 constants
// Format: 1 sign | 5 exponent | 10 mantissa
localparam FP16_0p0 = 16'h0000; // 0.0
localparam FP16_1p0 = 16'h3C00; // 1.0
localparam FP16_2p0 = 16'h4000; // 2.0
localparam FP16_3p0 = 16'h4200; // 3.0
localparam FP16_4p0 = 16'h4400; // 4.0
localparam FP16_5p0 = 16'h4500; // 5.0
localparam FP16_6p0 = 16'h4600; // 6.0
localparam FP16_0p5 = 16'h3800; // 0.5
localparam FP16_1p5 = 16'h3E00; // 1.5
localparam FP16_0p25 = 16'h3400; // 0.25
localparam FP16_1p75 = 16'h3F00; // 1.75
localparam FP16_2p5 = 16'h4100; // 2.5
localparam FP16_3p5 = 16'h4300; // 3.5
localparam FP16_N1p0 = 16'hBC00; // -1.0
localparam FP16_N2p0 = 16'hC000; // -2.0
localparam FP16_N0p5 = 16'hB800; // -0.5
localparam FP16_INF = 16'h7C00; // +Inf
localparam FP16_NINF = 16'hFC00; // -Inf
localparam FP16_QNAN = 16'h7E00; // canonical quiet NaN
task check;
input [15:0] expected;
input [63:0] test_id;
begin
#1;
if (result === expected) begin
$display("PASS: test %0d — a=0x%04h b=0x%04h result=0x%04h",
test_id, a, b, result);
pass_count = pass_count + 1;
end else begin
$display("FAIL: test %0d — a=0x%04h b=0x%04h got=0x%04h expected=0x%04h",
test_id, a, b, result, expected);
fail_count = fail_count + 1;
end
end
endtask
// Check NaN: any exponent=31 non-zero mantissa is acceptable
task check_nan;
input [63:0] test_id;
begin
#1;
if (result[14:10] == 5'h1F && result[9:0] != 10'h0) begin
$display("PASS: test %0d — NaN result=0x%04h (any NaN accepted)", test_id, result);
pass_count = pass_count + 1;
end else begin
$display("FAIL: test %0d — expected NaN got=0x%04h (exp[14:10] should be 5'h1F with non-zero mantissa)",
test_id, result);
fail_count = fail_count + 1;
end
end
endtask
initial begin
// --- Basic same-sign additions ---
a=FP16_1p0; b=FP16_1p0; check(FP16_2p0, 1); // 1+1=2
a=FP16_1p0; b=FP16_0p5; check(FP16_1p5, 2); // 1+0.5=1.5
a=FP16_1p5; b=FP16_0p25; check(FP16_1p75, 3); // 1.5+0.25=1.75
a=FP16_2p0; b=FP16_1p0; check(FP16_3p0, 4); // 2+1=3
a=FP16_3p0; b=FP16_3p0; check(FP16_6p0, 5); // 3+3=6 (carry-out → normalize)
// --- Subtraction (opposite signs) ---
a=FP16_1p0; b=FP16_N1p0; check(FP16_0p0, 6); // 1-1=0 (cancellation)
a=FP16_2p0; b=FP16_N1p0; check(FP16_1p0, 7); // 2-1=1
a=FP16_3p5; b=FP16_N0p5; check(FP16_3p0, 8); // 3.5-0.5=3 (normalization needed)
a=FP16_2p5; b=FP16_N1p0; check(FP16_1p5, 9); // 2.5-1=1.5
a=FP16_4p0; b=FP16_N2p0; check(FP16_2p0, 10); // 4-2=2
// --- Zero operands ---
a=FP16_0p0; b=FP16_5p0; check(FP16_5p0, 11); // 0+5=5
a=FP16_5p0; b=FP16_0p0; check(FP16_5p0, 12); // 5+0=5
a=FP16_0p0; b=FP16_0p0; check(FP16_0p0, 13); // 0+0=0
// --- Large exponent difference (alignment) ---
// 4.0 (exp=17) + 0.25 (exp=13) — difference=4, shift 0.25 right by 4
// 4.0 = 1.0000000000 × 2^2, 0.25 = 1.0000000000 × 2^-2
// 0.25 aligned to exp=2: 1.0000000000 >> 4 = 0.0001000000
// sum: 1.0000000000 + 0.0001000000 = 1.0001000000 × 2^2 = 4.25
// 4.25 = 0_10001_0001000000 = 0x4440
a=FP16_4p0; b=FP16_0p25; check(16'h4440, 14);
// --- Commutativity ---
a=FP16_0p5; b=FP16_1p0; check(FP16_1p5, 15); // 0.5+1 same as 1+0.5
// --- Negative + Negative ---
a=FP16_N1p0; b=FP16_N1p0; check(FP16_N2p0, 16); // -1-1=-2
// --- Special cases: Infinity ---
a=FP16_1p0; b=FP16_INF; check(FP16_INF, 17); // finite+inf=inf
a=FP16_INF; b=FP16_1p0; check(FP16_INF, 18); // inf+finite=inf
a=FP16_NINF; b=FP16_1p0; check(FP16_NINF, 19); // -inf+finite=-inf
// --- Special case: inf - inf = NaN ---
a=FP16_INF; b=FP16_NINF;
check_nan(20);
// --- NaN propagation ---
a=FP16_QNAN; b=FP16_1p0;
check_nan(21);
a=FP16_1p0; b=FP16_QNAN;
check_nan(22);
$display("SUMMARY: %0d passed, %0d failed", pass_count, fail_count);
$finish;
end
initial #10000 begin
$display("FAIL: timeout");
$finish;
end
endmodule
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