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https://github.com/drasko/codezero.git
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ba0e3ada21
Boot files and tasks are now initialised together. Theads can ask for particular space and thread ids, if they're unused. This enables us to get predefined ids for known tasks such as the VFS task. Fixes to README Other minor fixes.
65 lines
1.3 KiB
C
65 lines
1.3 KiB
C
/*
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* Bit manipulation functions.
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*
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* Copyright (C) 2007 Bahadir Balban
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*/
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#include <l4/lib/bit.h>
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#include INC_GLUE(memory.h)
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/* Emulation of ARM's CLZ (count leading zeroes) instruction */
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unsigned int __clz(unsigned int bitvector)
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{
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unsigned int x = 0;
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while((!(bitvector & ((unsigned)1 << 31))) && (x < 32)) {
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bitvector <<= 1;
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x++;
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}
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return x;
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}
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int find_and_set_first_free_bit(u32 *word, unsigned int limit)
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{
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int success = 0;
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int i;
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for(i = 0; i < limit; i++) {
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/* Find first unset bit */
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if (!(word[BITWISE_GETWORD(i)] & BITWISE_GETBIT(i))) {
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/* Set it */
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word[BITWISE_GETWORD(i)] |= BITWISE_GETBIT(i);
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success = 1;
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break;
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}
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}
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/* Return bit just set */
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if (success)
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return i;
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else
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return -1;
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}
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int check_and_clear_bit(u32 *word, int bit)
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{
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/* Check that bit was set */
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if (word[BITWISE_GETWORD(bit)] & BITWISE_GETBIT(bit)) {
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word[BITWISE_GETWORD(bit)] &= ~BITWISE_GETBIT(bit);
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return 0;
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} else {
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//printf("Trying to clear already clear bit\n");
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return -1;
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}
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}
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int check_and_set_bit(u32 *word, int bit)
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{
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/* Check that bit was clear */
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if (!(word[BITWISE_GETWORD(bit)] & BITWISE_GETBIT(bit))) {
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word[BITWISE_GETWORD(bit)] |= BITWISE_GETBIT(bit);
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return 0;
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} else {
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//printf("Trying to set already set bit\n");
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return -1;
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}
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}
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