82 lines
2.2 KiB
Text
82 lines
2.2 KiB
Text
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procedure multiplyBCD (m, n, u, v, w);
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comment
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Multiply array u of length m by array v of length n,
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putting the result in array w of length (m + n). the
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numbers are stored as binary coded decimal, most
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significant digit first.
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;
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value m, n;
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integer m, n;
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integer array u, v, w;
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begin
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integer i, j, carry, t;
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for j := 0 step 1 until n - 1 do
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begin
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if v[n - 1 - j] = 0 then
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begin
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comment (optional branch);
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w[n - 1 - j] := 0
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end
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else
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begin
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carry := 0;
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for i := 0 step 1 until m - 1 do
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begin
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t := (u[m - 1 - i] * v[n - 1 - j])
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+ w[m + n - 1 - i - j] + carry;
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carry := t % 10; comment (integer division);
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w[m + n - 1 - i - j] := t - (carry * 10)
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end;
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w[n - 1 - j] := carry
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end
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end
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end;
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procedure printBCD (m, u);
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value m;
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integer m;
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integer array u;
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begin
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integer i, j;
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comment Skip leading zeros;
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i := 0;
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for j := i while j < m - 1 & u[j] = 0 do
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i := i + 1;
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comment Print the digits, and separators;
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for j := i step 1 until m - 1 do
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begin
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if j != i & ((m - j) % 3) * 3 = m - j then
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begin
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comment Print UTF-8 for a narrow no-break space (U+202F);
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outstring (1, "\xE2\x80\xAF")
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end;
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outchar (1, "0123456789", u[j] + 1)
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end
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end;
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begin
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integer array u[0 : 19];
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integer array v[0 : 19];
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integer array w[0 : 39];
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u[0] := 1; u[1] := 8; u[2] := 4; u[3] := 4;
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u[4] := 6; u[5] := 7; u[6] := 4; u[7] := 4;
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u[8] := 0; u[9] := 7; u[10] := 3; u[11] := 7;
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u[12] := 0; u[13] := 9; u[14] := 5; u[15] := 5;
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u[16] := 1; u[17] := 6; u[18] := 1; u[19] := 6;
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v[0] := 1; v[1] := 8; v[2] := 4; v[3] := 4;
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v[4] := 6; v[5] := 7; v[6] := 4; v[7] := 4;
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v[8] := 0; v[9] := 7; v[10] := 3; v[11] := 7;
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v[12] := 0; v[13] := 9; v[14] := 5; v[15] := 5;
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v[16] := 1; v[17] := 6; v[18] := 1; v[19] := 6;
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multiplyBCD (20, 20, u, v, w);
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outstring (1, "u = "); printBCD (20, u); outstring (1, "\n");
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outstring (1, "v = "); printBCD (20, v); outstring (1, "\n");
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outstring (1, "u × v = "); printBCD (40, w); outstring (1, "\n")
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end
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