```c
#include
int main()
{
int num//定义一个变量num，用来存储需要转换的正整数
printf("请输入一个正整数:") //提示用户输入需要转换的正整数
scanf("%d",
已知字母A的ASCII码是01000001，则英文字母E的ASCII码是01000101。
ASCII码表中，大写英文字母是连续表。所以E在A后面第4位，所以E的ASCII码=01000001(二进制)+4(十进制)=01000101(二进制)。
后三位001变成101是因为这是二进制的运算，逢2进1。
ASCII码使用指定的7位或8位二进制数组合来表示128 或256 种可能的字符。标准ASCII码也叫基础ASCII码，使用7位二进制数来表示所有的大写和小写字母，数字0到9、标点符号，以及在美式英语中使用的特殊控制字符。
0～31及127(共33个)是控制字符或通信专用字符，它们并没有特定的图形显示，但会依不同的应用程序，而对文本显示有不同的影响。32～126(共95个)是字符，其中48～57为0到9的阿拉伯数字。
65～90为26个大写英文字母，97～122号为26个小写英文字母，其余为一些标点符号和运算符号等。
扩展资料：
大写英文字母ASCII码列表：
65：大写字母A
66：大写字母B
67：大写字母C
68：大写字母D
69：大写字母E
70：大写字母F
71：大写字母G
72：大写字母H
73：大写字母I
74：大写字母J
75：大写字母K
76：大写字母L
77：大写字母M
78：大写字母N
79：大写字母O
80：大写字母P
81：大写字母Q
82：大写字母R
83：大写字母S
84：大写字母T
85：大写字母U
86：大写字母V
87：大写字母W
88：大写字母X
89：大写字母Y
90：大写字母Z
参考资料来源：百度百科-ASCII
1、freq: IN INTEGER --控制输出波形的频率输入可以定义成integer吗？我觉的不行。
2、Qout : OUT integer
输出可以定义为integer吗？不知是如何输出的
3、 COMPONENT lpm_rom0
END COMPONENT
这句什么意思，多余的吧，此处定义元件是什么意思？
4、这段程序，逻辑上有问题，乱。
在此我给你一段三角波的程序：
entity sanjiao is
Port(rst : in std_logic
clk : in std_logic
q : out std_logic_vector(7 downto 0))
end sanjiao
architecture Behavioral of sanjiao is
begin
process(clk,rst)
variable num : std_logic_vector(7 downto 0)
variable ff :std_logic:='0'
begin
if(rst='1')then
num:="00000000"
elsif(clk'event and clk='1')then
if(ff='0')then
if(num="11111110")then
num:="11111111"
ff:='1'
else
num:=num+1
end if
elsif(ff='1')then
if(num="00000001")then
num:="00000000"
ff:='0'
else
num:=num-1
end if
end if
end if
q<=num
end process
end Behavioral
正弦波的程序：
entity sins is
Port ( clk : in std_logic
rst : in std_logic
q : out std_logic_vector(7 downto 0))
end sins
architecture Behavioral of sins is
signal a : std_logic_vector(7 downto 0)
signal b : std_logic_vector(7 downto 0)
begin
process(rst,clk)
begin
if(rst='1')then
a<=(others=>'0')
elsif(clk'event and clk='1')then
if (a="10110011") then
a<= "00000000"
else
a<=a+1
end if
end if
end process
process(a)
begin
case a is
when "00000000"=>b<="00000000"
when "00000001"=>b<="00000100"
when "00000010"=>b<="00001001"
when "00000011"=>b<="00001101"
when "00000100"=>b<="00010001"
when "00000101"=>b<="00010110"
when "00000110"=>b<="00011011"
when "00000111"=>b<="00011111"
when "00001000"=>b<="00100011"
when "00001001"=>b<="00101000"
when "00001010"=>b<="00101100"
when "00001011"=>b<="00110001"
when "00001100"=>b<="00110101"
when "00001101"=>b<="00111001"
when "00001110"=>b<="00111110"
when "00001111"=>b<="01000001"
when "00010000"=>b<="01000110"
when "00010001"=>b<="01001011"
when "00010010"=>b<="01001111"
when "00010011"=>b<="01010011"
when "00010100"=>b<="01010111"
when "00010101"=>b<="01011011"
when "00010110"=>b<="01100000"
when "00010111"=>b<="01100100"
when "00011000"=>b<="01101000"
when "00011001"=>b<="01101100"
when "00011010"=>b<="01110000"
when "00011011"=>b<="01110100"
when "00011100"=>b<="01111000"
when "00011101"=>b<="01111100"
when "00011110"=>b<="10000000"
when "00011111"=>b<="10000011"
when "00100000"=>b<="10000111"
when "00100001"=>b<="10001011"
when "00100010"=>b<="10001111"
when "00100011"=>b<="10010010"
when "00100100"=>b<="10010110"
when "00100101"=>b<="10011001"
when "00100110"=>b<="10011101"
when "00100111"=>b<="10100000"
when "00101000"=>b<="10100100"
when "00101001"=>b<="10100111"
when "00101010"=>b<="10101011"
when "00101011"=>b<="10101110"
when "00101100"=>b<="10110001"
when "00101101"=>b<="10110100"
when "00101110"=>b<="10110111"
when "00101111"=>b<="10111010"
when "00110000"=>b<="10111110"
when "00110001"=>b<="11000000"
when "00110010"=>b<="11000011"
when "00110011"=>b<="11000110"
when "00110100"=>b<="11001001"
when "00110101"=>b<="11001100"
when "00110110"=>b<="11001110"
when "00110111"=>b<="11010001"
when "00111000"=>b<="11010011"
when "00111001"=>b<="11010110"
when "00111010"=>b<="11011000"
when "00111011"=>b<="11011011"
when "00111100"=>b<="11011101"
when "00111101"=>b<="11011111"
when "00111110"=>b<="11100001"
when "00111111"=>b<="11100011"
when "01000000"=>b<="11100101"
when "01000001"=>b<="11100111"
when "01000010"=>b<="11101001"
when "01000011"=>b<="11101011"
when "01000100"=>b<="11101100"
when "01000101"=>b<="11101110"
when "01000110"=>b<="11110000"
when "01000111"=>b<="11110001"
when "01001000"=>b<="11110011"
when "01001001"=>b<="11110100"
when "01001010"=>b<="11110101"
when "01001011"=>b<="11110110"
when "01001100"=>b<="11110111"
when "01001101"=>b<="11111000"
when "01001110"=>b<="11111001"
when "01001111"=>b<="11111010"
when "01010000"=>b<="11111011"
when "01010001"=>b<="11111011"
when "01010010"=>b<="11111101"
when "01010011"=>b<="11111101"
when "01010100"=>b<="11111101"
when "01010101"=>b<="11111110"
when "01010110"=>b<="11111110"
when "01010111"=>b<="11111110"
when "01011000"=>b<="11111111"
when "01011001"=>b<="11111111"
when "01011010"=>b<="11111111"
when "01011011"=>b<="11111111"
when "01011100"=>b<="11111111"
when "01011101"=>b<="11111110"
when "01011110"=>b<="11111110"
when "01011111"=>b<="11111110"
when "01100000"=>b<="11111101"
when "01100001"=>b<="11111101"
when "01100010"=>b<="11111101"
when "01100011"=>b<="11111011"
when "01100100"=>b<="11111011"
when "01100101"=>b<="11111010"
when "01100110"=>b<="11111001"
when "01100111"=>b<="11111000"
when "01101000"=>b<="11110111"
when "01101001"=>b<="11110110"
when "01101010"=>b<="11110101"
when "01101011"=>b<="11110100"
when "01101100"=>b<="11110011"
when "01101101"=>b<="11110001"
when "01101110"=>b<="11110000"
when "01101111"=>b<="11101110"
when "01110000"=>b<="11101110"
when "01110001"=>b<="11101011"
when "01110010"=>b<="11101001"
when "01110011"=>b<="11100111"
when "01110100"=>b<="11100101"
when "01110101"=>b<="11100011"
when "01110110"=>b<="11100001"
when "01110111"=>b<="11011111"
when "01111000"=>b<="11011101"
when "01111001"=>b<="11011011"
when "01111010"=>b<="11011000"
when "01111011"=>b<="11010110"
when "01111100"=>b<="11010011"
when "01111101"=>b<="11010001"
when "01111110"=>b<="11001110"
when "01111111"=>b<="11001100"
when "10000000"=>b<="11001001"
when "10000001"=>b<="11000110"
when "10000010"=>b<="11000011"
when "10000011"=>b<="11000000"
when "10000100"=>b<="10111110"
when "10000101"=>b<="10111010"
when "10000110"=>b<="10110111"
when "10000111"=>b<="10110100"
when "10001000"=>b<="10110001"
when "10001001"=>b<="10101110"
when "10001010"=>b<="10101011"
when "10001011"=>b<="10100111"
when "10001100"=>b<="10100100"
when "10001101"=>b<="10100000"
when "10001110"=>b<="10011101"
when "10001111"=>b<="10011001"
when "10010000"=>b<="10010110"
when "10010001"=>b<="10010010"
when "10010010"=>b<="10001111"
when "10010011"=>b<="10001011"
when "10010100"=>b<="10000111"
when "10010101"=>b<="10000000"
when "10010110"=>b<="10000000"
when "10010111"=>b<="01111100"
when "10011000"=>b<="01111000"
when "10011001"=>b<="01110100"
when "10011010"=>b<="01110000"
when "10011011"=>b<="01101100"
when "10011100"=>b<="01101000"
when "10011101"=>b<="01100100"
when "10011110"=>b<="01100000"
when "10011111"=>b<="01011011"
when "10100000"=>b<="01010111"
when "10100001"=>b<="01010011"
when "10100010"=>b<="01001111"
when "10100011"=>b<="01001011"
when "10100100"=>b<="01000110"
when "10100101"=>b<="01000001"
when "10100110"=>b<="00111110"
when "10100111"=>b<="00111001"
when "10101000"=>b<="00110101"
when "10101001"=>b<="00110001"
when "10101010"=>b<="00101100"
when "10101011"=>b<="00101000"
when "10101100"=>b<="00100011"
when "10101101"=>b<="00011111"
when "10101110"=>b<="00011011"
when "10101111"=>b<="00010110"
when "10110000"=>b<="00010001"
when "10110001"=>b<="00001101"
when "10110010"=>b<="00001001"
when "10110011"=>b<="00000100"
-- when "10110100"=>b<="00000000"
when others=>null
end case
q(7 downto 0)<=b(7 downto 0)
end process
end Behavioral
锯齿波可以有三角波的程序来改。
你将这几段程序合在一起就可以了，可以用拨码开关对输出哪种波形进行选择，频率可以对输入的时钟进行分频来改变。
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