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FPU: Set FPSCR[FPRF] to zero for convert to integer operations

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This seems to be what P9 does.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This commit is contained in:
Paul Mackerras
2025-12-06 13:32:56 +11:00
parent 2f29daab2d
commit 0e11f80f2f
1 changed files with 17 additions and 12 deletions
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29
fpu.vhdl
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@@ -713,19 +713,24 @@ architecture behaviour of fpu is
end;
-- Determine result flags to write into the FPSCR
function result_flags(sign: std_ulogic; class: fp_number_class; unitbit: std_ulogic)
function result_flags(sign: std_ulogic; class: fp_number_class; int_result: std_ulogic;
unitbit: std_ulogic)
return std_ulogic_vector is
begin
case class is
when ZERO =>
return sign & "0010";
when FINITE =>
return (not unitbit) & sign & (not sign) & "00";
when INFINITY =>
return '0' & sign & (not sign) & "01";
when NAN =>
return "10001";
end case;
if int_result = '1' then
return "00000";
else
case class is
when ZERO =>
return sign & "0010";
when FINITE =>
return (not unitbit) & sign & (not sign) & "00";
when INFINITY =>
return '0' & sign & (not sign) & "01";
when NAN =>
return "10001";
end case;
end if;
end;
begin
@@ -3651,7 +3656,7 @@ begin
end if;
if r.update_fprf = '1' then
v.fpscr(FPSCR_C downto FPSCR_FU) := result_flags(r.res_sign, r.result_class,
v.fpscr(FPSCR_C downto FPSCR_FU) := result_flags(r.res_sign, r.result_class, r.int_result,
r.r(UNIT_BIT) and not r.denorm);
end if;