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)
17 prod1_lo <- prod1[XLEN:(XLEN*2)-1]
18 prod2 <- MULS(RB, diff)
19 prod2_lo <- prod2[XLEN:(XLEN*2)-1]
26 prod1_lo <- prod1_lo + round
27 prod2_lo <- prod2_lo + round
28 m <- MASK(n, (XLEN-1))
29 res1 <- ROTL64(prod1_lo, XLEN-n) & m
30 res2 <- ROTL64(prod2_lo, XLEN-n) & m
31 signbit1 <- prod1_lo[0]
32 signbit2 <- prod2_lo[0]
33 smask1 <- ([signbit1]*XLEN) & ¬m
34 smask2 <- ([signbit2]*XLEN) & ¬m
38 Special Registers Altered:
42 # [DRAFT] Integer Butterfly Multiply Add and Accumulate FFT/DCT
52 prod_lo <- prod[XLEN:(XLEN*2)-1]
57 res1 <- (RT) + prod_lo
58 res2 <- (RS) - prod_lo
65 m <- MASK(n, (XLEN-1))
66 res1 <- ROTL64(res1, XLEN-n) & m
67 res2 <- ROTL64(res2, XLEN-n) & m
68 smask1 <- ([signbit1]*XLEN) & ¬m
69 smask2 <- ([signbit2]*XLEN) & ¬m
73 Special Registers Altered: