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[/] [qaz_libs/] [trunk/] [basal/] [src/] [RAM/] [asym_ram_sdp_read_wider.v] - Rev 34

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// Asymmetric port RAM
// Read Wider than Write. Read Statement in loop
//asym_ram_sdp_read_wider.v
module asym_ram_sdp_read_wider (clkA, clkB, enaA, weA, enaB, addrA, addrB, diA, doB);
parameter WIDTHA = 4;
parameter SIZEA = 1024;
parameter ADDRWIDTHA = 10;
parameter WIDTHB = 16;
parameter SIZEB = 256;
parameter ADDRWIDTHB = 8;
input clkA;
input clkB;
input weA;
input enaA, enaB;
input [ADDRWIDTHA-1:0] addrA;
input [ADDRWIDTHB-1:0] addrB;
input [WIDTHA-1:0] diA;
output [WIDTHB-1:0] doB;
`define max(a,b) {(a) > (b) ? (a) : (b)}
`define min(a,b) {(a) < (b) ? (a) : (b)}
function integer log2;
input integer value;
reg [31:0] shifted;
integer res;
begin
if (value < 2)
log2 = value;
else
begin
shifted = value-1;
for (res=0; shifted>0; res=res+1)
shifted = shifted>>1;
log2 = res;
end
end
endfunction
localparam maxSIZE = `max(SIZEA, SIZEB);
localparam maxWIDTH = `max(WIDTHA, WIDTHB);
localparam minWIDTH = `min(WIDTHA, WIDTHB);
localparam RATIO = maxWIDTH / minWIDTH;
localparam log2RATIO = log2(RATIO);
reg [minWIDTH-1:0] RAM [0:maxSIZE-1];
reg [WIDTHB-1:0] readB;
always @(posedge clkA)
begin
if (enaA) begin
if (weA)
RAM[addrA] <= diA;
end
end
always @(posedge clkB)
begin : ramread
integer i;
reg [log2RATIO-1:0] lsbaddr;
if (enaB) begin
for (i = 0; i < RATIO; i = i+1) begin
lsbaddr = i;
readB[(i+1)*minWIDTH-1 -: minWIDTH] <= RAM[{addrB, lsbaddr}];
end
end
end
assign doB = readB;
endmodule
 

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