forked from M-Labs/nac3
135 lines
4.3 KiB
C
135 lines
4.3 KiB
C
#include "stdint.h"
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# define MAX(a, b) (a > b ? a : b)
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# define MIN(a, b) (a > b ? b : a)
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// adapted from GNU Scientific Library: https://git.savannah.gnu.org/cgit/gsl.git/tree/sys/pow_int.c
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// need to make sure `exp >= 0` before calling this function
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#define DEF_INT_EXP(T) T __nac3_int_exp_##T( \
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T base, \
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T exp \
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) { \
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T res = (T)1; \
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/* repeated squaring method */ \
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do { \
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if (exp & 1) res *= base; /* for n odd */ \
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exp >>= 1; \
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base *= base; \
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} while (exp); \
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return res; \
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} \
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DEF_INT_EXP(int32_t)
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DEF_INT_EXP(int64_t)
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DEF_INT_EXP(uint32_t)
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DEF_INT_EXP(uint64_t)
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int32_t __nac3_slice_index_bound(int32_t i, const int32_t len) {
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if (i < 0) {
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i = len + i;
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}
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if (i < 0) {
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return 0;
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} else if (i > len) {
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return len;
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}
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return i;
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}
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int32_t __nac3_range_slice_len(const int32_t start, const int32_t end, const int32_t step) {
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int32_t diff = end - start;
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if (diff > 0 && step > 0) {
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return ((diff - 1) / step) + 1;
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} else if (diff < 0 && step < 0) {
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return ((diff + 1) / step) + 1;
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} else {
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return 0;
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}
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}
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// Handle list assignment and dropping part of the list when
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// both dest_step and src_step are +1.
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// - All the index must *not* be out-of-bound or negative,
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// - The end index is *inclusive*,
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// - The length of src and dest slice size should already
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// be checked: if dest.step == 1 then len(src) <= len(dest) else len(src) == len(dest)
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int32_t __nac3_list_slice_assign_var_size(
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int32_t dest_start,
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int32_t dest_end,
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int32_t dest_step,
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uint8_t *dest_arr,
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int32_t dest_arr_len,
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int32_t src_start,
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int32_t src_end,
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int32_t src_step,
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uint8_t *src_arr,
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int32_t src_arr_len,
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const int32_t size
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) {
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/* if dest_arr_len == 0, do nothing since we do not support extending list */
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if (dest_arr_len == 0) return dest_arr_len;
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/* if both step is 1, memmove directly, handle the dropping of the list, and shrink size */
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if (src_step == dest_step && dest_step == 1) {
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const int32_t src_len = (src_end >= src_start) ? (src_end - src_start + 1) : 0;
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const int32_t dest_len = (dest_end >= dest_start) ? (dest_end - dest_start + 1) : 0;
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if (src_len > 0) {
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__builtin_memmove(
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dest_arr + dest_start * size,
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src_arr + src_start * size,
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src_len * size
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);
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}
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if (dest_len > 0) {
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/* dropping */
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__builtin_memmove(
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dest_arr + (dest_start + src_len) * size,
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dest_arr + (dest_end + 1) * size,
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(dest_arr_len - dest_end - 1) * size
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);
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}
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/* shrink size */
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return dest_arr_len - (dest_len - src_len);
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}
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/* if two range overlaps, need alloca */
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uint8_t need_alloca =
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(dest_arr == src_arr)
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&& !(
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MAX(dest_start, dest_end) < MIN(src_start, src_end)
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|| MAX(src_start, src_end) < MIN(dest_start, dest_end)
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);
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if (need_alloca) {
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uint8_t *tmp = __builtin_alloca(src_arr_len * size);
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__builtin_memcpy(tmp, src_arr, src_arr_len * size);
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src_arr = tmp;
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}
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int32_t src_ind = src_start;
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int32_t dest_ind = dest_start;
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for (;
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(src_step > 0) ? (src_ind <= src_end) : (src_ind >= src_end);
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src_ind += src_step, dest_ind += dest_step
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) {
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/* for constant optimization */
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if (size == 1) {
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__builtin_memcpy(dest_arr + dest_ind, src_arr + src_ind, 1);
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} else if (size == 4) {
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__builtin_memcpy(dest_arr + dest_ind * 4, src_arr + src_ind * 4, 4);
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} else if (size == 8) {
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__builtin_memcpy(dest_arr + dest_ind * 8, src_arr + src_ind * 8, 8);
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} else {
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/* memcpy for var size, cannot overlap after previous alloca */
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__builtin_memcpy(dest_arr + dest_ind * size, src_arr + src_ind * size, size);
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}
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}
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/* only dest_step == 1 can we shrink the dest list. */
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/* size should be ensured prior to calling this function */
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if (dest_step == 1 && dest_end >= dest_start) {
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__builtin_memmove(
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dest_arr + dest_ind * size,
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dest_arr + (dest_end + 1) * size,
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(dest_arr_len - dest_end - 1) * size
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);
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return dest_arr_len - (dest_end - dest_ind) - 1;
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}
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return dest_arr_len;
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} |