/*- * Copyright (c) 1991 The Regents of the University of California. * All rights reserved. * * This code is derived from software contributed to Berkeley by * Ralph Campbell. * * %sccs.include.redist.c% */ #include #if defined(LIBC_SCCS) && !defined(lint) ASMSTR("@(#)bcopy.s 5.4 (Berkeley) 07/26/92") #endif /* LIBC_SCCS and not lint */ /* bcopy(s1, s2, n) */ #include #if BYTE_ORDER == LITTLE_ENDIAN # define LWHI lwr # define LWLO lwl # define SWHI swr # define SWLO swl #endif #if BYTE_ORDER == BIG_ENDIAN # define LWHI lwl # define LWLO lwr # define SWHI swl # define SWLO swr #endif LEAF(bcopy) .set noreorder addu t0, a0, a2 # t0 = end of s1 region sltu t1, a1, t0 sltu t2, a0, a1 and t1, t1, t2 # t1 = true if from < to < (from+len) beq t1, zero, forward # non overlapping, do forward copy slt t2, a2, 12 # check for small copy ble a2, zero, 2f addu t1, a1, a2 # t1 = end of to region 1: lb v0, -1(t0) # copy bytes backwards, subu t0, t0, 1 # doesn't happen often so do slow way subu t1, t1, 1 bne t0, a0, 1b sb v0, 0(t1) 2: j ra nop forward: bne t2, zero, smallcpy # do a small bcopy xor v0, a0, a1 # compare low two bits of addresses and v0, v0, 3 subu a3, zero, a1 # compute # bytes to word align address beq v0, zero, aligned # addresses can be word aligned and a3, a3, 3 beq a3, zero, 1f subu a2, a2, a3 # subtract from remaining count LWHI v0, 0(a0) # get next 4 bytes (unaligned) LWLO v0, 3(a0) addu a0, a0, a3 SWHI v0, 0(a1) # store 1, 2, or 3 bytes to align a1 addu a1, a1, a3 1: and v0, a2, 3 # compute number of words left subu a3, a2, v0 move a2, v0 addu a3, a3, a0 # compute ending address 2: LWHI v0, 0(a0) # copy words a0 unaligned, a1 aligned LWLO v0, 3(a0) addu a0, a0, 4 addu a1, a1, 4 bne a0, a3, 2b sw v0, -4(a1) b smallcpy nop aligned: beq a3, zero, 1f subu a2, a2, a3 # subtract from remaining count LWHI v0, 0(a0) # copy 1, 2, or 3 bytes to align addu a0, a0, a3 SWHI v0, 0(a1) addu a1, a1, a3 1: and v0, a2, 3 # compute number of whole words left subu a3, a2, v0 move a2, v0 addu a3, a3, a0 # compute ending address 2: lw v0, 0(a0) # copy words addu a0, a0, 4 addu a1, a1, 4 bne a0, a3, 2b sw v0, -4(a1) smallcpy: ble a2, zero, 2f addu a3, a2, a0 # compute ending address 1: lbu v0, 0(a0) # copy bytes addu a0, a0, 1 addu a1, a1, 1 bne a0, a3, 1b sb v0, -1(a1) 2: j ra nop .set reorder END(bcopy)