| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame^] | 1 | /* |
| 2 | * arch/alpha/lib/strncpy.S |
| 3 | * Contributed by Richard Henderson (rth@tamu.edu) |
| 4 | * |
| 5 | * Copy no more than COUNT bytes of the null-terminated string from |
| 6 | * SRC to DST. If SRC does not cover all of COUNT, the balance is |
| 7 | * zeroed. |
| 8 | * |
| 9 | * Or, rather, if the kernel cared about that weird ANSI quirk. This |
| 10 | * version has cropped that bit o' nastiness as well as assuming that |
| 11 | * __stxncpy is in range of a branch. |
| 12 | */ |
| 13 | |
| 14 | .set noat |
| 15 | .set noreorder |
| 16 | |
| 17 | .text |
| 18 | |
| 19 | .align 4 |
| 20 | .globl strncpy |
| 21 | .ent strncpy |
| 22 | strncpy: |
| 23 | .frame $30, 0, $26 |
| 24 | .prologue 0 |
| 25 | |
| 26 | mov $16, $0 # set return value now |
| 27 | beq $18, $zerolen |
| 28 | unop |
| 29 | bsr $23, __stxncpy # do the work of the copy |
| 30 | |
| 31 | unop |
| 32 | bne $18, $multiword # do we have full words left? |
| 33 | subq $24, 1, $3 # nope |
| 34 | subq $27, 1, $4 |
| 35 | |
| 36 | or $3, $24, $3 # clear the bits between the last |
| 37 | or $4, $27, $4 # written byte and the last byte in COUNT |
| 38 | andnot $4, $3, $4 |
| 39 | zap $1, $4, $1 |
| 40 | |
| 41 | stq_u $1, 0($16) |
| 42 | ret |
| 43 | |
| 44 | .align 4 |
| 45 | $multiword: |
| 46 | subq $24, 1, $2 # clear the final bits in the prev word |
| 47 | or $2, $24, $2 |
| 48 | zapnot $1, $2, $1 |
| 49 | subq $18, 1, $18 |
| 50 | |
| 51 | stq_u $1, 0($16) |
| 52 | addq $16, 8, $16 |
| 53 | unop |
| 54 | beq $18, 1f |
| 55 | |
| 56 | nop |
| 57 | unop |
| 58 | nop |
| 59 | blbc $18, 0f |
| 60 | |
| 61 | stq_u $31, 0($16) # zero one word |
| 62 | subq $18, 1, $18 |
| 63 | addq $16, 8, $16 |
| 64 | beq $18, 1f |
| 65 | |
| 66 | 0: stq_u $31, 0($16) # zero two words |
| 67 | subq $18, 2, $18 |
| 68 | stq_u $31, 8($16) |
| 69 | addq $16, 16, $16 |
| 70 | bne $18, 0b |
| 71 | |
| 72 | 1: ldq_u $1, 0($16) # clear the leading bits in the final word |
| 73 | subq $27, 1, $2 |
| 74 | or $2, $27, $2 |
| 75 | |
| 76 | zap $1, $2, $1 |
| 77 | stq_u $1, 0($16) |
| 78 | $zerolen: |
| 79 | ret |
| 80 | |
| 81 | .end strncpy |