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27 | */ |
27 | */ |
28 | 28 | ||
29 | #ifndef __MIPS_ATOMIC_H__ |
29 | #ifndef __MIPS_ATOMIC_H__ |
30 | #define __MIPS_ATOMIC_H__ |
30 | #define __MIPS_ATOMIC_H__ |
31 | 31 | ||
32 | #define atomic_inc(x) ((*x)++) |
32 | #define atomic_inc(x) (a_add(x,1)) |
33 | #define atomic_dec(x) ((*x)--) |
33 | #define atomic_dec(x) (a_sub(x,1)) |
- | 34 | ||
- | 35 | /* |
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- | 36 | * Atomic addition |
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- | 37 | * |
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- | 38 | * This case is harder, and we have to use the special LL and SC operations |
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- | 39 | * to achieve atomicity. The instructions are similar to LW (load) and SW |
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- | 40 | * (store), except that the LL (load-linked) instruction loads the address |
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- | 41 | * of the variable to a special register and if another process writes to |
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- | 42 | * the same location, the SC (store-conditional) instruction fails. |
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- | 43 | */ |
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- | 44 | static inline int a_add( volatile int *val, int i) |
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- | 45 | { |
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- | 46 | int tmp, tmp2; |
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- | 47 | ||
- | 48 | asm volatile ( |
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- | 49 | " .set push\n" |
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- | 50 | " .set noreorder\n" |
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- | 51 | " nop\n" |
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- | 52 | "1:\n" |
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- | 53 | " ll %0, %1\n" |
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- | 54 | " addu %0, %0, %2\n" |
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- | 55 | " move %3, %0\n" |
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- | 56 | " sc %0, %1\n" |
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- | 57 | " beq %0, 0x0, 1b\n" |
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- | 58 | " move %0, %3\n" |
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- | 59 | " .set pop\n" |
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- | 60 | : "=&r" (tmp), "=o" (*val) |
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- | 61 | : "r" (i), "r" (tmp2) |
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- | 62 | ); |
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- | 63 | return tmp; |
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- | 64 | } |
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- | 65 | ||
- | 66 | ||
- | 67 | /* |
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- | 68 | * Atomic subtraction |
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- | 69 | * |
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- | 70 | * Implemented in the same manner as a_add, except we substract the value. |
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- | 71 | */ |
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- | 72 | static inline int a_sub( volatile int *val, int i) |
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- | 73 | ||
- | 74 | { |
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- | 75 | int tmp, tmp2; |
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- | 76 | ||
- | 77 | asm volatile ( |
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- | 78 | " .set push\n" |
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- | 79 | " .set noreorder\n" |
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- | 80 | " nop\n" |
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- | 81 | "1:\n" |
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- | 82 | " ll %0, %1\n" |
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- | 83 | " subu %0, %0, %2\n" |
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- | 84 | " move %3, %0\n" |
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- | 85 | " sc %0, %1\n" |
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- | 86 | " beq %0, 0x0, 1b\n" |
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- | 87 | " move %0, %3\n" |
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- | 88 | " .set pop\n" |
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- | 89 | : "=&r" (tmp), "=o" (*val) |
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- | 90 | : "r" (i), "r" (tmp2) |
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- | 91 | ); |
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- | 92 | return tmp; |
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- | 93 | } |
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- | 94 | ||
34 | 95 | ||
35 | #endif |
96 | #endif |