Fix XLEN != 64 cases where maddsubrs fails

[openpower-isa.git] / openpower / isa / butterfly.mdwn

diff --git a/openpower/isa/butterfly.mdwn b/openpower/isa/butterfly.mdwn
index ec10679339fcf512fe5e4cef77031eb81b009b48..b6b7efe523c4ee9c9e61dd1fc6ce5ab96d3d7121 100644 (file)
--- a/openpower/isa/butterfly.mdwn
+++ b/openpower/isa/butterfly.mdwn
@@ -14,26 +14,43 @@ Pseudo-code:
     sum <- (RT) + (RA)
     diff <- (RT) - (RA)
     prod1 <- MULS(RB, sum)
-    prod1_lo <- prod1[XLEN:(XLEN*2)-1]
     prod2 <- MULS(RB, diff)
-    prod2_lo <- prod2[XLEN:(XLEN*2)-1]
     if n = 0 then
+        prod1_lo <- prod1[XLEN:(XLEN*2)-1]
+        prod2_lo <- prod2[XLEN:(XLEN*2)-1]
         RT <- prod1_lo
         RS <- prod2_lo
     else
-        round <- [0]*XLEN
-        round[XLEN -n] <- 1
-        prod1_lo <- prod1_lo + round
-        prod2_lo <- prod2_lo + round
-        m <- MASK(n, (XLEN-1))
-        res1 <- ROTL64(prod1_lo, XLEN-n) & m
-        res2 <- ROTL64(prod2_lo, XLEN-n) & m
-        signbit1 <- prod1_lo[0]
-        signbit2 <- prod2_lo[0]
-        smask1 <- ([signbit1]*XLEN) & ¬m
-        smask2 <- ([signbit2]*XLEN) & ¬m
-        RT <- (res1 | smask1)
-        RS <- (res2 | smask2)
+        if XLEN = 64 then
+            prod1_lo <- prod1[XLEN:(XLEN*2)-1]
+            prod2_lo <- prod2[XLEN:(XLEN*2)-1]
+            round <- [0]*XLEN
+            round[XLEN -n] <- 1
+            prod1_lo <- prod1_lo + round
+            prod2_lo <- prod2_lo + round
+            m <- MASK(n, (XLEN-1))
+            res1 <- ROTL64(prod1_lo, XLEN-n) & m
+            res2 <- ROTL64(prod2_lo, XLEN-n) & m
+            signbit1 <- prod1_lo[0]
+            signbit2 <- prod2_lo[0]
+            smask1 <- ([signbit1]*XLEN) & ¬m
+            smask2 <- ([signbit2]*XLEN) & ¬m
+            RT <- (res1 | smask1)
+            RS <- (res2 | smask2)
+        else
+            round <- [0]*(XLEN*2)
+            round[XLEN*2 -n] <- 1
+            prod1 <- prod1 + round
+            prod2 <- prod2 + round
+            m <- MASK(XLEN-n, XLEN-1)
+            res1 <- prod1[XLEN-n:XLEN*2 -n -1]
+            res2 <- prod2[XLEN-n:XLEN*2 -n -1]
+            signbit1 <- prod1[0]
+            signbit2 <- prod2[0]
+            smask1 <- ([signbit1]*XLEN) & ¬m
+            smask2 <- ([signbit2]*XLEN) & ¬m
+            RT <- (res1 | smask1)
+            RS <- (res2 | smask2)
 
 Special Registers Altered:
 
@@ -49,47 +66,44 @@ Pseudo-code:
 
     n <- SH
     prod <- MULS(RB, RA)
-    prod_lo <- prod[XLEN:(XLEN*2)-1]
     if n = 0 then
+        prod_lo <- prod[XLEN:(XLEN*2)-1]
         RT <- (RT) + prod_lo
+        RS <- (RS) - prod_lo
     else
-        res <- (RT) + prod_lo
-        round <- [0]*XLEN
-        round[XLEN -n] <- 1
-        res <- res + round
-        signbit <- res[0]
-        m <- MASK(n, (XLEN-1))
-        res <- ROTL64(res, XLEN-n) & m
-        smask <- ([signbit]*XLEN) & ¬m
-        RT <- (res | smask)
-
-Special Registers Altered:
-
-    None
-
-# [DRAFT] Integer Butterfly Multiply Subtract From FFT/DCT 
-
-A-Form
-
-* msubrs  RT,RA,SH,RB
-
-Pseudo-code:
-
-    n <- SH
-    prod <- MULS(RB, RA)
-    prod_lo <- prod[XLEN:(XLEN*2)-1]
-    if n = 0 then
-        RT <- (RT) - prod_lo
-    else
-        res <- (RT) - prod_lo
-        round <- [0]*XLEN
-        round[XLEN -n] <- 1
-        res <- res + round
-        signbit <- res[0]
-        m <- MASK(n, (XLEN-1))
-        res <- ROTL64(res, XLEN-n) & m
-        smask <- ([signbit]*XLEN) & ¬m
-        RT <- (res | smask)
+        if XLEN = 64 then
+            prod_lo <- prod[XLEN:(XLEN*2)-1]
+            res1 <- (RT) + prod_lo
+            res2 <- (RS) - prod_lo
+            round <- [0]*XLEN
+            round[XLEN -n] <- 1
+            res1 <- res1 + round
+            res2 <- res2 + round
+            signbit1 <- res1[0]
+            signbit2 <- res2[0]
+            m <- MASK(n, (XLEN-1))
+            res1 <- ROTL64(res1, XLEN-n) & m
+            res2 <- ROTL64(res2, XLEN-n) & m
+            smask1 <- ([signbit1]*XLEN) & ¬m
+            smask2 <- ([signbit2]*XLEN) & ¬m
+            RT <- (res1 | smask1)
+            RS <- (res2 | smask2)
+        else
+            res1 <- (RT) + prod
+            res2 <- (RS) - prod
+            round <- [0]*XLEN*2
+            round[XLEN*2 -n] <- 1
+            res1 <- res1 + round
+            res2 <- res2 + round
+            signbit1 <- res1[0]
+            signbit2 <- res2[0]
+            m <- MASK(XLEN-n, (XLEN-1))
+            res1 <- prod1[XLEN-n:XLEN*2 -n -1]
+            res2 <- prod2[XLEN-n:XLEN*2 -n -1]
+            smask1 <- ([signbit1]*XLEN) & ¬m
+            smask2 <- ([signbit2]*XLEN) & ¬m
+            RT <- (res1 | smask1)
+            RS <- (res2 | smask2)
 
 Special Registers Altered: