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Added STACKADDR parameter

This commit is contained in:
Clifford Wolf 2016-06-07 17:05:02 +02:00
parent f4bb91b060
commit bf062e39ac
2 changed files with 15 additions and 1 deletions
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8
README.md
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@ -279,6 +279,14 @@ The start address of the program.
The start address of the interrupt handler.
#### STACKADDR (default = 32'h ffff_ffff)
When this parameter has a value different from 0xffffffff, then register `x2` (the
stack pointer) is initialized to this value on reset. (All other registers remain
uninitialized.) Note that the RISC-V calling convention requires the stack pointer
to be aligned on 16 bytes boundaries (4 bytes for the RV32I soft float calling
convention).
Cycles per Instruction Performance
----------------------------------

8
picorv32.v
View File

@ -61,7 +61,8 @@ module picorv32 #(
parameter [31:0] MASKED_IRQ = 32'h 0000_0000,
parameter [31:0] LATCHED_IRQ = 32'h ffff_ffff,
parameter [31:0] PROGADDR_RESET = 32'h 0000_0000,
parameter [31:0] PROGADDR_IRQ = 32'h 0000_0010
parameter [31:0] PROGADDR_IRQ = 32'h 0000_0010,
parameter [31:0] STACKADDR = 32'h ffff_ffff
) (
input clk, resetn,
output reg trap,
@ -1162,6 +1163,11 @@ module picorv32 #(
irq_state <= 0;
eoi <= 0;
timer <= 0;
if (~STACKADDR) begin
latched_store <= 1;
latched_rd <= 2;
reg_out <= STACKADDR;
end
cpu_state <= cpu_state_fetch;
end else
(* parallel_case, full_case *)