📄 checksum.s
字号:
/* checksum.S: Sparc V9 optimized checksum code. * * Copyright(C) 1995 Linus Torvalds * Copyright(C) 1995 Miguel de Icaza * Copyright(C) 1996, 2000 David S. Miller * Copyright(C) 1997 Jakub Jelinek * * derived from: * Linux/Alpha checksum c-code * Linux/ix86 inline checksum assembly * RFC1071 Computing the Internet Checksum (esp. Jacobsons m68k code) * David Mosberger-Tang for optimized reference c-code * BSD4.4 portable checksum routine */ .textcsum_partial_fix_alignment: /* We checked for zero length already, so there must be * at least one byte. */ be,pt %icc, 1f nop ldub [%o0 + 0x00], %o4 add %o0, 1, %o0 sub %o1, 1, %o11: andcc %o0, 0x2, %g0 be,pn %icc, csum_partial_post_align cmp %o1, 2 blu,pn %icc, csum_partial_end_cruft nop lduh [%o0 + 0x00], %o5 add %o0, 2, %o0 sub %o1, 2, %o1 ba,pt %xcc, csum_partial_post_align add %o5, %o4, %o4 .align 32 .globl csum_partialcsum_partial: /* %o0=buff, %o1=len, %o2=sum */ prefetch [%o0 + 0x000], #n_reads clr %o4 prefetch [%o0 + 0x040], #n_reads brz,pn %o1, csum_partial_finish andcc %o0, 0x3, %g0 /* We "remember" whether the lowest bit in the address * was set in %g7. Because if it is, we have to swap * upper and lower 8 bit fields of the sum we calculate. */ bne,pn %icc, csum_partial_fix_alignment andcc %o0, 0x1, %g7csum_partial_post_align: prefetch [%o0 + 0x080], #n_reads andncc %o1, 0x3f, %o3 prefetch [%o0 + 0x0c0], #n_reads sub %o1, %o3, %o1 brz,pn %o3, 2f prefetch [%o0 + 0x100], #n_reads /* So that we don't need to use the non-pairing * add-with-carry instructions we accumulate 32-bit * values into a 64-bit register. At the end of the * loop we fold it down to 32-bits and so on. */ prefetch [%o0 + 0x140], #n_reads1: lduw [%o0 + 0x00], %o5 lduw [%o0 + 0x04], %g1 lduw [%o0 + 0x08], %g2 add %o4, %o5, %o4 lduw [%o0 + 0x0c], %g3 add %o4, %g1, %o4 lduw [%o0 + 0x10], %o5 add %o4, %g2, %o4 lduw [%o0 + 0x14], %g1 add %o4, %g3, %o4 lduw [%o0 + 0x18], %g2 add %o4, %o5, %o4 lduw [%o0 + 0x1c], %g3 add %o4, %g1, %o4 lduw [%o0 + 0x20], %o5 add %o4, %g2, %o4 lduw [%o0 + 0x24], %g1 add %o4, %g3, %o4 lduw [%o0 + 0x28], %g2 add %o4, %o5, %o4 lduw [%o0 + 0x2c], %g3 add %o4, %g1, %o4 lduw [%o0 + 0x30], %o5 add %o4, %g2, %o4 lduw [%o0 + 0x34], %g1 add %o4, %g3, %o4 lduw [%o0 + 0x38], %g2 add %o4, %o5, %o4 lduw [%o0 + 0x3c], %g3 add %o4, %g1, %o4 prefetch [%o0 + 0x180], #n_reads add %o4, %g2, %o4 subcc %o3, 0x40, %o3 add %o0, 0x40, %o0 bne,pt %icc, 1b add %o4, %g3, %o42: and %o1, 0x3c, %o3 brz,pn %o3, 2f sub %o1, %o3, %o11: lduw [%o0 + 0x00], %o5 subcc %o3, 0x4, %o3 add %o0, 0x4, %o0 bne,pt %icc, 1b add %o4, %o5, %o42: /* fold 64-->32 */ srlx %o4, 32, %o5 srl %o4, 0, %o4 add %o4, %o5, %o4 srlx %o4, 32, %o5 srl %o4, 0, %o4 add %o4, %o5, %o4 /* fold 32-->16 */ sethi %hi(0xffff0000), %g1 srl %o4, 16, %o5 andn %o4, %g1, %g2 add %o5, %g2, %o4 srl %o4, 16, %o5 andn %o4, %g1, %g2 add %o5, %g2, %o4csum_partial_end_cruft: /* %o4 has the 16-bit sum we have calculated so-far. */ cmp %o1, 2 blu,pt %icc, 1f nop lduh [%o0 + 0x00], %o5 sub %o1, 2, %o1 add %o0, 2, %o0 add %o4, %o5, %o41: brz,pt %o1, 1f nop ldub [%o0 + 0x00], %o5 sub %o1, 1, %o1 add %o0, 1, %o0 sllx %o5, 8, %o5 add %o4, %o5, %o41: /* fold 32-->16 */ sethi %hi(0xffff0000), %g1 srl %o4, 16, %o5 andn %o4, %g1, %g2 add %o5, %g2, %o4 srl %o4, 16, %o5 andn %o4, %g1, %g2 add %o5, %g2, %o41: brz,pt %g7, 1f nop /* We started with an odd byte, byte-swap the result. */ srl %o4, 8, %o5 and %o4, 0xff, %g1 sll %g1, 8, %g1 or %o5, %g1, %o41: add %o2, %o4, %o2csum_partial_finish: retl mov %o2, %o0⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -