Github_Repos/cvw
1
0
Fork 1
mirror of https://github.com/openhwgroup/cvw synced 2025-02-11 06:05:49 +00:00
Code Issues Packages Projects Releases Wiki Activity

removed the +1 in the cvt

Browse Source
This commit is contained in:
Katherine Parry 2022-07-13 09:41:35 -07:00
parent 3c1bea1104
commit b45b3baec2
1 changed files with 13 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
pipelined/src/fpu/fcvt.sv
View File

@ -68,6 +68,7 @@ module fcvt (
logic Signed; // is the opperation with a signed integer? logic Signed; // is the opperation with a signed integer?
logic Int64; // is the integer 64 bits? logic Int64; // is the integer 64 bits?
logic IntToFp; // is the opperation an int->fp conversion? logic IntToFp; // is the opperation an int->fp conversion?
logic [`CVTLEN:0] LzcInFull; // input to the Leading Zero Counter (priority encoder)
logic [`LOGCVTLEN-1:0] LeadingZeros; // output from the LZC logic [`LOGCVTLEN-1:0] LeadingZeros; // output from the LZC
@ -102,10 +103,11 @@ module fcvt (
// choose the input to the leading zero counter i.e. priority encoder // choose the input to the leading zero counter i.e. priority encoder
// int -> fp : | positive integer | 00000... (if needed) | // int -> fp : | positive integer | 00000... (if needed) |
// fp -> fp : | fraction | 00000... (if needed) | // fp -> fp : | fraction | 00000... (if needed) |
assign LzcIn = IntToFp ? {TrimInt, {`CVTLEN-`XLEN{1'b0}}} : assign LzcInFull = IntToFp ? {1'b0, TrimInt, {`CVTLEN-`XLEN{1'b0}}} :
{Xm[`NF-1:0], {`CVTLEN-`NF{1'b0}}}; {Xm, {`CVTLEN-`NF{1'b0}}};
assign LzcIn = LzcInFull[`CVTLEN-1:0];
lzc #(`CVTLEN) lzc (.num(LzcIn), .ZeroCnt(LeadingZeros)); lzc #(`CVTLEN+1) lzc (.num(LzcInFull), .ZeroCnt(LeadingZeros));
/////////////////////////////////////////////////////////////////////////// ///////////////////////////////////////////////////////////////////////////
// shifter // shifter
@ -119,13 +121,13 @@ module fcvt (
// denormalized/undeflowed result fp -> fp: // denormalized/undeflowed result fp -> fp:
// - shift left by NF-1+CalcExp - to shift till the biased expoenent is 0 // - shift left by NF-1+CalcExp - to shift till the biased expoenent is 0
// ??? -> fp: // ??? -> fp:
// - shift left by LeadingZeros+1 - to shift till the result is normalized // - shift left by LeadingZeros - to shift till the result is normalized
// - only shift fp -> fp if the intital value is denormalized // - only shift fp -> fp if the intital value is denormalized
// - this is a problem because the input to the lzc was the fraction rather than the mantissa // - this is a problem because the input to the lzc was the fraction rather than the mantissa
// - rather have a few and-gates than an extra bit in the priority encoder??? *** is this true? // - rather have a few and-gates than an extra bit in the priority encoder??? *** is this true?
assign ShiftAmt = ToInt ? Ce[`LOGCVTLEN-1:0]&{`LOGCVTLEN{~Ce[`NE]}} : assign ShiftAmt = ToInt ? Ce[`LOGCVTLEN-1:0]&{`LOGCVTLEN{~Ce[`NE]}} :
ResDenormUf&~IntToFp ? (`LOGCVTLEN)'(`NF-1)+Ce[`LOGCVTLEN-1:0] : ResDenormUf&~IntToFp ? (`LOGCVTLEN)'(`NF-1)+Ce[`LOGCVTLEN-1:0] :
(LeadingZeros+1)&{`LOGCVTLEN{XDenorm|IntToFp}}; (LeadingZeros)&{`LOGCVTLEN{XDenorm|IntToFp}};
/////////////////////////////////////////////////////////////////////////// ///////////////////////////////////////////////////////////////////////////
// exp calculations // exp calculations
@ -197,14 +199,14 @@ module fcvt (
// | 0's | Mantissa | 0's if nessisary | // | 0's | Mantissa | 0's if nessisary |
// | keep | // | keep |
// //
// - if the input is denormalized then we dont shift... so the "- (LeadingZeros+1)" is just leftovers from other options // - if the input is denormalized then we dont shift... so the "- LeadingZeros" is just leftovers from other options
// int -> fp : largest bias + XLEN - Largest bias + new bias - 1 - LeadingZeros = XLEN + NewBias - 1 - LeadingZeros // int -> fp : largest bias + XLEN - Largest bias + new bias - LeadingZeros = XLEN + NewBias - LeadingZeros
// Process: // Process:
// - shifted right by XLEN (XLEN) // - shifted right by XLEN (XLEN)
// - shift left to normilize (-1-LeadingZeros) // - shift left to normilize (-LeadingZeros)
// - newBias to make the biased exponent // - newBias to make the biased exponent
// oldexp - biasold +newbias - (LeadingZeros+1)&(XDenorm|IntToFp) // oldexp - biasold +newbias - LeadingZeros&(XDenorm|IntToFp)
assign Ce = {1'b0, OldExp} - (`NE+1)'(`BIAS) + {2'b0, NewBias} - {{`NE{1'b0}}, XDenorm|IntToFp} - {{`NE-`LOGCVTLEN+1{1'b0}}, (LeadingZeros&{`LOGCVTLEN{XDenorm|IntToFp}})}; assign Ce = {1'b0, OldExp} - (`NE+1)'(`BIAS) + {2'b0, NewBias} - {{`NE-`LOGCVTLEN+1{1'b0}}, (LeadingZeros&{`LOGCVTLEN{XDenorm|IntToFp}})};
// find if the result is dnormal or underflows // find if the result is dnormal or underflows
// - if Calculated expoenent is 0 or negitive (and the input/result is not exactaly 0) // - if Calculated expoenent is 0 or negitive (and the input/result is not exactaly 0)
// - can't underflow an integer to Fp conversion // - can't underflow an integer to Fp conversion