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fdivsqrt parameter cleanup

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This commit is contained in:
David Harris 2023-11-10 18:33:08 -08:00
parent 3cae2385ab
commit d5ba8fc5e6
3 changed files with 8 additions and 4 deletions
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10
config/shared/config-shared.vh
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@ -93,11 +93,17 @@ localparam NF2 = ((F_SUPPORTED & (LEN1 != S_LEN)) ? S_NF : H_NF);
localparam FMT2 = ((F_SUPPORTED & (LEN1 != S_LEN)) ? 2'd0 : 2'd2);
localparam BIAS2 = ((F_SUPPORTED & (LEN1 != S_LEN)) ? S_BIAS : H_BIAS);
// intermediate division parameters not directly used in Divider
localparam FPDIVN = NF+3; // length of floating-point inputs: Ns + 2 = Nf + 3 for 1 integer bit, Nf fracitonal bits, 2 extra bits to shift sqrt into [1/4, 1)]
localparam DIVN = ((FPDIVN<XLEN) & IDIV_ON_FPU) ? XLEN : FPDIVN+3; // standard length of input: max(XLEN, NF+2) ***
// division constants
localparam DIVN = ((NF+2<XLEN) & IDIV_ON_FPU) ? XLEN : NF+2; // standard length of input: max(XLEN, NF+2)
// *** define NF+2, justify, use in DIVN
localparam LOGR = $clog2(RADIX); // r = log(R)
localparam RK = LOGR*DIVCOPIES; // r*k bits per cycle generated
localparam FPDUR = (DIVN+1)/RK + 1 + (RADIX/4); // *** relate to algorithm for rest of these
//localparam FPDUR = (DIVN+1)/RK + 1 + (RADIX/4); // *** relate to algorithm for rest of these
localparam FPDUR = (DIVN+LOGR-1)/RK + 1 ; // ceiling((DIVN+LOGR)/RK)
localparam DURLEN = $clog2(FPDUR+1);
localparam DIVb = FPDUR*RK - 1; // canonical fdiv size (b)
localparam DIVBLEN = $clog2(DIVb+2)-1; // *** where is 2 coming from?

1
config/shared/parameter-defs.vh
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@ -177,7 +177,6 @@ localparam cvw_t P = '{
NORMSHIFTSZ : NORMSHIFTSZ,
LOGNORMSHIFTSZ : LOGNORMSHIFTSZ,
CORRSHIFTSZ : CORRSHIFTSZ,
DIVN : DIVN,
LOGR : LOGR,
RK : RK,
FPDUR : FPDUR,

1
src/cvw.sv
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@ -269,7 +269,6 @@ typedef struct packed {
int CORRSHIFTSZ;
// division constants
int DIVN ;
int LOGR ;
int RK ;
int FPDUR ;