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|
`include "core/uarch.sv"
module core_psr
(
input logic clk,
rst_n,
write,
saved,
wr_flags,
wr_control,
escalating,
update_flags,
alu_v_valid,
input psr_flags alu_flags,
input word psr_wr,
output psr_flags flags,
output psr_intmask mask,
output psr_mode mode,
output word cpsr_rd,
spsr_rd,
output logic privileged
);
typedef struct packed
{
psr_flags flags;
psr_intmask mask;
psr_mode mode;
} psr_state;
typedef struct packed
{
psr_flags nzcv;
logic q;
logic[1:0] reserved0;
logic j;
logic[3:0] reserved1,
ge;
logic[5:0] reserved2;
logic e;
logic a;
psr_intmask if_;
logic t;
psr_mode m;
} psr_word;
psr_word cpsr_word /*verilator public*/, spsr_word, wr_word;
psr_flags next_flags;
psr_state cpsr, spsr, spsr_svc, spsr_abt, spsr_und, spsr_irq, spsr_fiq,
wr_state, wr_clean;
assign mode = cpsr.mode;
assign mask = cpsr.mask;
assign flags = cpsr.flags;
assign wr_word = psr_wr;
assign cpsr_rd = cpsr_word;
assign spsr_rd = spsr_word;
assign privileged = |mode[3:0]; // Not user
assign {wr_state.flags, wr_state.mask, wr_state.mode} = {wr_word.nzcv, wr_word.if_, wr_word.m};
`ifdef VERILATOR
psr_word spsr_svc_word /*verilator public*/,
spsr_abt_word /*verilator public*/,
spsr_und_word /*verilator public*/,
spsr_fiq_word /*verilator public*/,
spsr_irq_word /*verilator public*/;
always_comb begin
spsr_svc_word = {$bits(spsr_svc_word){1'b0}};
spsr_abt_word = {$bits(spsr_abt_word){1'b0}};
spsr_und_word = {$bits(spsr_und_word){1'b0}};
spsr_irq_word = {$bits(spsr_irq_word){1'b0}};
spsr_fiq_word = {$bits(spsr_fiq_word){1'b0}};
spsr_svc_word.a = 1;
spsr_abt_word.a = 1;
spsr_und_word.a = 1;
spsr_irq_word.a = 1;
spsr_fiq_word.a = 1;
{spsr_svc_word.nzcv, spsr_svc_word.if_, spsr_svc_word.m}
= {spsr_svc.flags, spsr_svc.mask, spsr_svc.mode};
{spsr_abt_word.nzcv, spsr_abt_word.if_, spsr_abt_word.m}
= {spsr_abt.flags, spsr_abt.mask, spsr_abt.mode};
{spsr_und_word.nzcv, spsr_und_word.if_, spsr_und_word.m}
= {spsr_und.flags, spsr_und.mask, spsr_und.mode};
{spsr_irq_word.nzcv, spsr_irq_word.if_, spsr_irq_word.m}
= {spsr_irq.flags, spsr_irq.mask, spsr_irq.mode};
{spsr_fiq_word.nzcv, spsr_fiq_word.if_, spsr_fiq_word.m}
= {spsr_fiq.flags, spsr_fiq.mask, spsr_fiq.mode};
end
`endif
always_comb begin
next_flags = alu_flags;
if(!alu_v_valid)
next_flags.v = flags.v;
unique case(mode)
`MODE_SVC: spsr = spsr_svc;
`MODE_ABT: spsr = spsr_abt;
`MODE_UND: spsr = spsr_und;
`MODE_IRQ: spsr = spsr_irq;
`MODE_FIQ: spsr = spsr_fiq;
default: spsr = cpsr;
endcase
cpsr_word = {$bits(cpsr_word){1'b0}};
spsr_word = {$bits(spsr_word){1'b0}};
{cpsr_word.a, spsr_word.a} = 2'b11;
{cpsr_word.nzcv, cpsr_word.if_, cpsr_word.m} = {flags, mask, mode};
{spsr_word.nzcv, spsr_word.if_, spsr_word.m} = {spsr.flags, spsr.mask, spsr.mode};
wr_clean = wr_state;
unique case(wr_state.mode)
`MODE_USR, `MODE_FIQ, `MODE_IRQ, `MODE_SVC,
`MODE_ABT, `MODE_UND, `MODE_SYS: ;
default:
wr_clean.mode = mode;
endcase
if(!wr_flags)
wr_clean.flags = flags;
if(!wr_control) begin
wr_clean.mask = mask;
wr_clean.mode = mode;
end
if(mode == `MODE_USR && !escalating) begin
wr_clean.mask = mask;
wr_clean.mode = `MODE_USR;
end
end
always_ff @(posedge clk or negedge rst_n)
if(!rst_n) begin
cpsr.mode <= `MODE_SVC;
cpsr.flags <= 4'b0000;
cpsr.mask.i <= 1;
cpsr.mask.f <= 1;
spsr_svc <= {$bits(spsr_svc){1'b0}};
spsr_abt <= {$bits(spsr_svc){1'b0}};
spsr_und <= {$bits(spsr_svc){1'b0}};
spsr_irq <= {$bits(spsr_svc){1'b0}};
spsr_fiq <= {$bits(spsr_svc){1'b0}};
end else begin
if(!write) begin
if(update_flags)
cpsr.flags <= next_flags;
end else if(!saved)
cpsr <= wr_clean;
else
unique case(mode)
`MODE_SVC: spsr_svc <= wr_clean;
`MODE_ABT: spsr_abt <= wr_clean;
`MODE_UND: spsr_und <= wr_clean;
`MODE_IRQ: spsr_irq <= wr_clean;
`MODE_FIQ: spsr_fiq <= wr_clean;
default: ;
endcase
end
endmodule
|
