1 <!-- SVP64 Butterfly DCT Instructions here described are based on -->
3 <!-- PLEASE NOTE THESE ARE UNAPPROVED AND DRAFT, NOT SUBMITTED TO OPF ISA WG -->
5 # [DRAFT] Integer Butterfly Multiply Add/Sub FFT/DCT
9 * maddsubrs RT,RA,SH,RB
16 prod1 <- MULS(RB, sum)[XLEN:(XLEN*2)-1]
17 prod2 <- MULS(RB, diff)[XLEN:(XLEN*2)-1]
18 res1 <- ROTL64(prod1, XLEN-n)
19 res2 <- ROTL64(prod2, XLEN-n)
20 m <- MASK(n, (XLEN-1))
23 smask1 <- ([s1]*XLEN) & ¬m
24 smask2 <- ([s2]*XLEN) & ¬m
25 RT <- res1 & m | smask1
26 RS <- res2 & m | smask2
28 Special Registers Altered: