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verilog中数据类型real

news 2025/11/6 7:12:43

在 Verilog 中，real 是一种实数数据类型，用于表示浮点数（双精度浮点数）。

一、基本特性

real 表示64位双精度浮点数
遵循 IEEE 754 标准
主要用于仿真和建模，通常不可综合
默认初始值为 0.0

二、语法和用法

real variable_name;
real [array_size] array_name;

三、基本操作示例

module real_example;real temperature;real voltage, current;real pi = 3.1415926535;initial begin// 基本赋值temperature = 25.5;voltage = 3.3;current = 0.15;$display("Temperature: %f", temperature);$display("Voltage: %f, Current: %f", voltage, current);$display("PI: %f", pi);// 数学运算real power;power = voltage * current;$display("Power: %f", power);// 科学计数法real avogadro = 6.022e23;$display("Avogadro's number: %e", avogadro);end
endmodule

四、数学运算

module real_math_operations;real a, b, c;real result;initial begina = 10.5;b = 3.2;// 基本运算result = a + b;      // 加法$display("a + b = %f", result);result = a - b;      // 减法$display("a - b = %f", result);result = a * b;      // 乘法$display("a * b = %f", result);result = a / b;      // 除法$display("a / b = %f", result);// 数学函数result = $sqrt(a);   // 平方根$display("sqrt(a) = %f", result);result = $ln(a);     // 自然对数$display("ln(a) = %f", result);result = $exp(b);    // 指数$display("exp(b) = %f", result);result = $sin(a);    // 正弦$display("sin(a) = %f", result);result = $pow(a, b); // 幂运算$display("a^b = %f", result);end
endmodule

五、实际应用场景

1. 模拟电路建模

module analog_model;real v_in, v_out;real r1 = 1000.0;  // 1kΩreal r2 = 2000.0;  // 2kΩreal gain;initial begin// 计算运放增益gain = 1.0 + (r2 / r1);$display("Amplifier gain: %f", gain);// 模拟输入输出关系for (v_in = 0.0; v_in <= 5.0; v_in = v_in + 0.5) beginv_out = v_in * gain;$display("Vin=%f V, Vout=%f V", v_in, v_out);endend
endmodule

2. 温度传感器模型

module temperature_sensor;real temp_c;        // 摄氏度real temp_f;        // 华氏度real voltage_out;   // 输出电压real sensitivity = 0.01;  // 10mV/°Ctask measure_temperature;input real ambient_temp;begintemp_c = ambient_temp;temp_f = (temp_c * 9.0/5.0) + 32.0;voltage_out = temp_c * sensitivity;$display("Temperature: %f°C (%f°F)", temp_c, temp_f);$display("Output voltage: %f V", voltage_out);endendtaskinitial beginmeasure_temperature(25.0);  // 室温#10;measure_temperature(100.0); // 沸水温度end
endmodule

3. 物理系统仿真

module physics_simulation;real time_step = 0.001;  // 1ms 时间步长real time = 0.0;real position = 0.0;real velocity = 10.0;    // 初始速度 10 m/sreal acceleration = -9.8; // 重力加速度initial begin$display("Time(s) Position(m) Velocity(m/s)");while (position >= 0.0) begin$display("%f %f %f", time, position, velocity);// 更新物理量position = position + velocity * time_step;velocity = velocity + acceleration * time_step;time = time + time_step;#1;  // 仿真时间推进end$display("Object hit ground at time: %f s", time);end
endmodule

六、与整数类型的转换

module real_conversion;real float_val;integer int_val;reg [31:0] fixed_val;initial beginfloat_val = 123.456;// real → integer (截断)int_val = float_val;$display("Real: %f -> Integer: %d", float_val, int_val);// real → fixed point (Q格式)fixed_val = float_val * 256.0;  // Q8.24格式$display("Real: %f -> Fixed: %h", float_val, fixed_val);// integer → realfloat_val = 100;$display("Integer 100 -> Real: %f", float_val);// 使用系统函数转换float_val = 45.67;int_val = $rtoi(float_val);  // 四舍五入到整数$display("$rtoi(%f) = %d", float_val, int_val);float_val = $itor(89);       // 整数转实数$display("$itor(89) = %f", float_val);end
endmodule

七、实数数组

module real_array_example;real data_set [0:9];  // 10个实数的数组real matrix [0:2][0:2];  // 3x3 实数矩阵real average, sum;integer i, j;initial begin// 初始化数组for (i = 0; i < 10; i = i + 1) begindata_set[i] = i * 1.5;end// 计算平均值sum = 0.0;for (i = 0; i < 10; i = i + 1) beginsum = sum + data_set[i];endaverage = sum / 10.0;$display("Average: %f", average);// 矩阵操作for (i = 0; i < 3; i = i + 1) beginfor (j = 0; j < 3; j = j + 1) beginmatrix[i][j] = i * 3.0 + j * 1.0;endendend
endmodule

八、系统函数和任务

module real_system_functions;real val1, val2;initial beginval1 = 2.5;val2 = -1.8;// 数学函数$display("abs(%f) = %f", val2, $abs(val2));$display("floor(%f) = %f", val1, $floor(val1));$display("ceil(%f) = %f", val1, $ceil(val1));// 随机实数生成$display("Random real: %f", $random % 100 * 0.01);// 比较函数if ($greater(val1, val2)) begin$display("%f is greater than %f", val1, val2);endend
endmodule