![]() ![]() Of course there is no such thing as a free lunch, because of the added logic the path from the BRAM became to long and I needed to reduce the speed from 100MHz to about 80MHz.This could be fixed by adding an extra IM3 stage to the IM1, and IM2 stages, so the output of the BRAM can be registered, and so the logic path is divided into two shorter paths. I also added a flush for the jump and branch instructions. That kind of worked except for the jump and branch instructions, so I implemented a forwarding unit that forwarded the register values of the ME1, ME2, and WB stage to the EX stage so there didn’t need to be any nop instructions in code stream. Li a3, 0x10000000 lui a2, 0x989 li a5, 0 nop nop nop l1: sw a5, 0 ( a3 ) nop nop nop addi a4, a2, 1664 nop nop nop addi a5, a5, 1 nop nop nop l2: addi a4, a4 ,- 1 nop nop nop bnez a4, l2 nop nop nop j l1 The line if2_to_id_buf <= reset_if2_to_id_buf in the code uses the constant reset_if2_to_id_buf to reset the signals, the constant is defined in a library like this ![]() nop := '0' end if next_if2_to_id_buf <= v end process if2_to_id_buf_o <= if2_to_id_buf end behavioral nop = '1' or ibus_stall_i = '1' ) then v. To get a bit of an overview, I quickly setup VHDL entities for all 7 pipeline stages and started to implement and connect them with Vivado.Įntity if2_stage is port ( if1_to_if2_buf_i : in if1_to_if2_buf_type if2_to_id_buf_o : out if2_to_id_buf_type flush_i : in std_logic stall_i : in std_logic ibus_dat_i : in std_logic_vector ( 31 downto 0 ) ibus_stall_i : in std_logic clk_i : in std_logic rst_i : in std_logic ) end if2_stage architecture behavioral of if2_stage is signal if2_to_id_buf : if2_to_id_buf_type signal next_if2_to_id_buf : if2_to_id_buf_type begin process ( clk_i, rst_i, next_if2_to_id_buf ) begin if ( rising_edge ( clk_i )) then if ( rst_i = '1' ) then if2_to_id_buf <= reset_if2_to_id_buf else if2_to_id_buf <= next_if2_to_id_buf end if end if end process process ( if2_to_id_buf, if1_to_if2_buf_i, ibus_dat_i, ibus_stall_i, flush_i ) variable v : if2_to_id_buf_type begin v := if2_to_id_buf v. So instructions are read from port A and data is read and written to port B, which kind of makes the BRAM its own arbiter. To do that there must be some arbiter, but here I cheated a bit, and used the BRAM dual port feature. The next problem was that the pipeline design is a Harvard architecture, so the IF stage and ME stage would want to access RAM at the same time. So my 5 stage pipeline design turned into a 7 stage pipeline design, with IF1, IF1, ID, EX, ME1, ME2, and WB. But BRAM has a 1 (or 2) clock delay, before that data is available on the output. When trying to implement the IF (Instruction Fetch) stage I ran into problems, because I wanted to use the Xilinx BRAM as memory. So I started working on a classic 5-Stage pipelined RISC-V core, and that’s when the learning experience begun. The goal wasn’t so much to end up with a usable RISC-V core, but to learn more VHDL, after my initial Merry x-Mas try out. Since I only had 2 weeks vacation, and inventing a whole universe would have been to much work, I skipped a few parts and started with designing a RISC-V core. The famous quote from Carl Sagan could also be applied to computer science, if you want to make a program from scratch you must first invent the universe. Allow to cool before serving (the longer it cools, the more the filling will set and will be easier to slice).If you wish to make an apple pie from scratch, you must first invent the universe. Remove from the oven and transfer to a cooling rack. Transfer to the oven and bake until the juices from the apples are bubbling and the crust is golden brown, 45-55 minutes. Pour in the melted butter and use a fork to mix until you have large clumps.Īdd the prepared apple wedges to the pie crust. Add the 1/2 cup all purpose flour, 1/2 cup almond flour, 1/2 cup brown sugar, 1/4 teaspoon ground cinnamon, and salt to a medium bowl and mix to combine. Toss the apple wedges with the lemon zest and juice, 1/4 cup brown sugar, 3 tablespoons flour, 2 tablespoons melted butter, 1/2 teaspoon cinnamon and salt. Peel, core, and slice the apples into 1/4-inch wedges. Line a 9-inch pie plate with crust, or set aside a store bought pie crust. Preheat the oven to 350 degrees and place a rack in the center of the oven. ![]() Pennsylvania Dutch Apple Pie Recipe Crust & Filling Ingredients:ġ pie crust (store bought works fine here!)ġ/4 cup light or dark brown sugar (packed)ĭash of salt Dutch Apple Pie Crumble Topping:ġ/2 cup light or dark brown sugar (packed) ![]()
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