From: Ben Pfaff Date: Wed, 15 Dec 2004 06:53:22 +0000 (+0000) Subject: Clean up. X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4d02c49e21ba884fd5d3dc092b3834641e3b742a;p=pintos-anon Clean up. --- diff --git a/src/lib/kernel/bitmap.c b/src/lib/kernel/bitmap.c index 009482d..88a5e7e 100644 --- a/src/lib/kernel/bitmap.c +++ b/src/lib/kernel/bitmap.c @@ -111,16 +111,16 @@ bitmap_size (const struct bitmap *b) return b->bit_cnt; } -/* Sets the bit numbered IDX in B to VALUE. */ +/* Atomically sets the bit numbered IDX in B to VALUE. */ void bitmap_set (struct bitmap *b, size_t idx, bool value) { ASSERT (b != NULL); ASSERT (idx < b->bit_cnt); if (value) - b->bits[elem_idx (idx)] |= bit_mask (idx); + bitmap_mark (b, idx); else - b->bits[elem_idx (idx)] &= ~bit_mask (idx); + bitmap_reset (b, idx); } /* Sets all bits in B to VALUE. */ @@ -146,35 +146,45 @@ bitmap_set_multiple (struct bitmap *b, size_t start, size_t cnt, bool value) bitmap_set (b, start + i, value); } -/* Atomically sets the bit numbered IDX in B to true. */ +/* Atomically sets the bit numbered BIT_IDX in B to true. */ void -bitmap_mark (struct bitmap *b, size_t idx) +bitmap_mark (struct bitmap *b, size_t bit_idx) { - asm ("orl %1, %0" - : "=m" (b->bits[elem_idx (idx)]) - : "r" (bit_mask (idx))); + size_t idx = elem_idx (bit_idx); + elem_type mask = bit_mask (bit_idx); + + /* This is equivalent to `b->bits[idx] |= mask' except that it + is guaranteed to be atomic on a uniprocessor machine. See + the description of the OR instruction in [IA32-v2b]. */ + asm ("orl %1, %0" : "=m" (b->bits[idx]) : "r" (mask) : "cc"); } -/* Atomically sets the bit numbered IDX in B to false. */ +/* Atomically sets the bit numbered BIT_IDX in B to false. */ void -bitmap_reset (struct bitmap *b, size_t idx) +bitmap_reset (struct bitmap *b, size_t bit_idx) { - asm ("andl %1, %0" - : "=m" (b->bits[elem_idx (idx)]) - : "r" (~bit_mask (idx))); + size_t idx = elem_idx (bit_idx); + elem_type mask = bit_mask (idx); + + /* This is equivalent to `b->bits[idx] &= ~mask' except that it + is guaranteed to be atomic on a uniprocessor machine. See + the description of the AND instruction in [IA32-v2a]. */ + asm ("andl %1, %0" : "=m" (b->bits[idx]) : "r" (~mask) : "cc"); } /* Atomically toggles the bit numbered IDX in B; that is, if it is true, makes it false, and if it is false, makes it true. */ void -bitmap_flip (struct bitmap *b, size_t idx) +bitmap_flip (struct bitmap *b, size_t bit_idx) { - ASSERT (b != NULL); - ASSERT (idx < b->bit_cnt); - asm ("xorl %1, %0" - : "=m" (b->bits[elem_idx (idx)]) - : "r" (bit_mask (idx))); + size_t idx = elem_idx (bit_idx); + elem_type mask = bit_mask (idx); + + /* This is equivalent to `b->bits[idx] ^= mask' except that it + is guaranteed to be atomic on a uniprocessor machine. See + the description of the XOR instruction in [IA32-v2b]. */ + asm ("xorl %1, %0" : "=m" (b->bits[idx]) : "r" (mask) : "cc"); } /* Returns the value of the bit numbered IDX in B. */ @@ -210,15 +220,17 @@ contains (const struct bitmap *b, size_t start, size_t cnt, bool value) size_t bitmap_scan (const struct bitmap *b, size_t start, size_t cnt, bool value) { - size_t idx, last; - ASSERT (b != NULL); ASSERT (start <= b->bit_cnt); - if (cnt <= b->bit_cnt) - for (idx = start, last = b->bit_cnt - cnt; idx <= last; idx++) - if (!contains (b, idx, cnt, !value)) - return idx; + if (cnt <= b->bit_cnt) + { + size_t last = b->bit_cnt - cnt; + size_t i; + for (i = start; i <= last; i++) + if (!contains (b, i, cnt, !value)) + return i; + } return BITMAP_ERROR; }