--- /dev/null
+/*
+ * Copyright (c) 2006 Apple Computer, Inc. All rights reserved.
+ *
+ * @APPLE_LICENSE_HEADER_START@
+ *
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ *
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ *
+ * @APPLE_LICENSE_HEADER_END@
+ */
+
+#include <mach/machine/asm.h>
+
+/*
+ * A reasonably well-optimized bzero/memset. Should work equally well on arm11 and arm9 based
+ * cores.
+ *
+ * The algorithm is to align the destination pointer on a 32 byte boundary and then
+ * blast data 64 bytes at a time, in two stores of 32 bytes per loop.
+ */
+ .text
+ .align 2
+
+ .globl _memset
+/* void *memset(void *ptr, int c, size_t len); */
+_memset:
+ /* move len into r1, unpack c into r2 */
+ mov r3, r2
+ and r1, r1, #0xff
+ orr r1, r1, r1, lsl #8
+ orr r2, r1, r1, lsl #16
+ mov r1, r3
+ b Lbzeroengine
+
+ .globl _bzero
+/* void bzero(void *ptr, size_t len); */
+_bzero:
+ /* zero out r2 so we can be just like memset(0) */
+ mov r2, #0
+
+Lbzeroengine:
+ /* move the base pointer into r12 and leave r0 alone so that we return the original pointer */
+ mov r12, r0
+
+ /* copy r2 into r3 for 64-bit stores */
+ mov r3, r2
+
+ /* check for zero len */
+ cmp r1, #0
+ bxeq lr
+
+ /* fall back to a bytewise store for less than 32 bytes */
+ cmp r1, #32
+ blt L_bytewise
+
+ /* check for 32 byte unaligned ptr */
+ tst r12, #0x1f
+ bne L_unaligned
+
+ /* make sure we have more than 64 bytes to zero */
+ cmp r1, #64
+ blt L_lessthan64aligned
+
+ /* >= 64 bytes of len, 32 byte aligned */
+L_64ormorealigned:
+
+ /* we need some registers, avoid r7 (frame pointer) and r9 (thread register) */
+ stmfd sp!, { r4-r6, r8, r10-r11 }
+ mov r4, r2
+ mov r5, r2
+ mov r6, r2
+ mov r8, r2
+ mov r10, r2
+ mov r11, r2
+
+ /* pre-subtract 64 from the len to avoid an extra compare in the loop */
+ sub r1, r1, #64
+
+L_64loop:
+ stmia r12!, { r2-r6, r8, r10-r11 }
+ subs r1, r1, #64
+ stmia r12!, { r2-r6, r8, r10-r11 }
+ bge L_64loop
+
+ /* restore the saved regs */
+ ldmfd sp!, { r4-r6, r8, r10-r11 }
+
+ /* check for completion (had previously subtracted an extra 64 from len) */
+ adds r1, r1, #64
+ bxeq lr
+
+L_lessthan64aligned:
+ /* do we have 16 or more bytes left */
+ cmp r1, #16
+ stmgeia r12!, { r2-r3 }
+ stmgeia r12!, { r2-r3 }
+ subges r1, r1, #16
+ bgt L_lessthan64aligned
+ bxeq lr
+
+L_lessthan16aligned:
+ /* store 0 to 15 bytes */
+ mov r1, r1, lsl #28 /* move the remaining len bits [3:0] to the flags area of cpsr */
+ msr cpsr_f, r1
+
+ stmmiia r12!, { r2-r3 } /* n is set, store 8 bytes */
+ streq r2, [r12], #4 /* z is set, store 4 bytes */
+ strcsh r2, [r12], #2 /* c is set, store 2 bytes */
+ strvsb r2, [r12], #1 /* v is set, store 1 byte */
+ bx lr
+
+L_bytewise:
+ /* bytewise copy, 2 bytes at a time, alignment not guaranteed */
+ subs r1, r1, #2
+ strb r2, [r12], #1
+ strplb r2, [r12], #1
+ bhi L_bytewise
+ bx lr
+
+L_unaligned:
+ /* unaligned on 32 byte boundary, store 1-15 bytes until we're 16 byte aligned */
+ mov r3, r12, lsl #28
+ rsb r3, r3, #0x00000000
+ msr cpsr_f, r3
+
+ strvsb r2, [r12], #1 /* v is set, unaligned in the 1s column */
+ strcsh r2, [r12], #2 /* c is set, unaligned in the 2s column */
+ streq r2, [r12], #4 /* z is set, unaligned in the 4s column */
+ strmi r2, [r12], #4 /* n is set, unaligned in the 8s column */
+ strmi r2, [r12], #4
+
+ subs r1, r1, r3, lsr #28
+ bxeq lr
+
+ /* we had previously trashed r3, restore it */
+ mov r3, r2
+
+ /* now make sure we're 32 byte aligned */
+ tst r12, #(1 << 4)
+ stmneia r12!, { r2-r3 }
+ stmneia r12!, { r2-r3 }
+ subnes r1, r1, #16
+
+ /* we're now aligned, check for >= 64 bytes left */
+ cmp r1, #64
+ bge L_64ormorealigned
+ b L_lessthan64aligned
+
projects / apple / libc.git / blobdiff