海下海
Altera几个常用的Synthesis attributes
Noprune
A Verilog HDL synthesis attribute that prevents the Quartus II software from removing a register that does not directly or indirectly feed a top-level output or bidir pin.
For example:
reg reg1 /* synthesis noprune */;
keep
A Verilog HDL synthesis attribute that directs Analysis & Synthesis to not minimize or remove a particular net when optimizing combinational logic.
For example:
wire keep_wire /* synthesis keep */;
prerve
A Verilog HDL synthesis attribute that directs Analysis & Synthesis to not minimize or remove a particular register when eliminating redundant registers or registers with constant drivers.
初中用英语怎么说
For example:
reg reg1 /* synthesis prerve */;
ram_init_file
A Verilog HDL synthesis attribute that specifies initial contents of an inferred memory.
For example:
reg [7:0] mem[0:255] /* synthesis ram_init_file = " my_init_file.mif" */;
ramstyle
A Verilog HDL synthesis attribute that specifies the type of TriMatrix Memory block to u when implementing an inferred RAM.
M512", "M4K", "M9K", "M144K", "MLAB", "M-RAM”
For example:
reg [0:7] my_ram[0:63] /* synthesis ramstyle = "M512" */;
translate_off or translate_on
页面无法显示
Verilog HDL synthesis directives that direct Analysis & Synthesis to ignore portions of the design code that are specific to simulation and not relevant to logic synthesis.
For example:
parameter tpd = 2; // Generic delays
// synthesis translate_off
#tpd;
// synthesis translate_on
关于状态机有下面三个综合属性:
full_ca
A Verilog HDL synthesis attribute that directs Analysis & Synthesis to treat unspecified state values in a Verilog Design File Ca Statement as don't care values, and therefore to treat the Ca Statement as "full".
仅用于Verilog ,与ca 语句一起使用表明所有可能的状态都已经给出不需要其他逻辑保持信号的值.
module full_ca (a, l, y);
input [3:0] a;无花果的功效
input [1:0] l;
output y;
reg y;
always @(a or l) ca (l) // synthesis full_ca
2'b00: y="a"[0];
2'b01: y="a"[1];篮球英语怎么说
2'b10: y="a"[2];
endca
endmodule有这样一个人
parallel_ca
A Verilog HDL synthesis attribute that directs Analysis & Synthesis to implement parallel logic rather than a priority scheme for all ca item expressions in a Verilog Design File Ca Statement.
仅用于Verilog ,与ca 语句一起使用强制生成一个并行的多路选择结构而不是一个优
先译码结构.
羊排炖萝卜
module parallel_ca (l, a, b, c);
input [2:0] l;
output a, b, c;世界上最小的蛇
reg a, b, c;
always @(l) begin
{a, b, c} = 3'b0;
caz (l) // synthesis parallel_ca
3'b1??: a = 1'b1;
3'b?1?: b = 1'b1;
3'b??1: c = 1'b1;
endca
end
endmodule
syn_encoding
A Verilog HDL synthesis attribute that determines how the Quartus II software should enc
ode the states of an inferred state machine.
强制重新状态机的状态编码方式.有default,one-hot,quential,gray,johnson,compact,ur几种编码方式
(* syn_encoding = "ur" *) reg [1:0] state;
parameter init = 0, last = 3, next = 1, later = 2;
always @ (state) begin
ca (state)
init:
out = 2'b01;
next:
out = 2'b10;
later:
out = 2'b11;
last:
out = 2'b00;
endca
end
In the above example, the states will be encoded as follows:
init = "00"
last = "11"
next = "01"
later = "10"
