--- /dev/null
+/*
+ * Copyright 1992 by Jutta Degener and Carsten Bormann, Technische
+ * Universitaet Berlin. See the accompanying file "COPYRIGHT" for
+ * details. THERE IS ABSOLUTELY NO WARRANTY FOR THIS SOFTWARE.
+ */
+
+/*
+ * See private.h for the more commonly used macro versions.
+ */
+
+#include <stdio.h>
+#include <assert.h>
+
+#include "gsm610_priv.h"
+
+#define saturate(x) \
+ ((x) < MIN_WORD ? MIN_WORD : (x) > MAX_WORD ? MAX_WORD: (x))
+
+word gsm_add ( word a, word b)
+{
+ longword sum = (longword)a + (longword)b;
+ return saturate(sum);
+}
+
+word gsm_sub ( word a, word b)
+{
+ longword diff = (longword)a - (longword)b;
+ return saturate(diff);
+}
+
+word gsm_mult ( word a, word b)
+{
+ if (a == MIN_WORD && b == MIN_WORD)
+ return MAX_WORD;
+
+ return SASR_L( (longword)a * (longword)b, 15 );
+}
+
+word gsm_mult_r ( word a, word b)
+{
+ if (b == MIN_WORD && a == MIN_WORD) return MAX_WORD;
+ else {
+ longword prod = (longword)a * (longword)b + 16384;
+ prod >>= 15;
+ return prod & 0xFFFF;
+ }
+}
+
+word gsm_abs (word a)
+{
+ return a < 0 ? (a == MIN_WORD ? MAX_WORD : -a) : a;
+}
+
+longword gsm_L_mult (word a, word b)
+{
+ assert( a != MIN_WORD || b != MIN_WORD );
+ return ((longword)a * (longword)b) << 1;
+}
+
+longword gsm_L_add ( longword a, longword b)
+{
+ if (a < 0) {
+ if (b >= 0) return a + b;
+ else {
+ ulongword A = (ulongword)-(a + 1) + (ulongword)-(b + 1);
+ return A >= MAX_LONGWORD ? MIN_LONGWORD :-(longword)A-2;
+ }
+ }
+ else if (b <= 0) return a + b;
+ else {
+ ulongword A = (ulongword)a + (ulongword)b;
+ return A > MAX_LONGWORD ? MAX_LONGWORD : A;
+ }
+}
+
+longword gsm_L_sub ( longword a, longword b)
+{
+ if (a >= 0) {
+ if (b >= 0) return a - b;
+ else {
+ /* a>=0, b<0 */
+
+ ulongword A = (ulongword)a + -(b + 1);
+ return A >= MAX_LONGWORD ? MAX_LONGWORD : (A + 1);
+ }
+ }
+ else if (b <= 0) return a - b;
+ else {
+ /* a<0, b>0 */
+
+ ulongword A = (ulongword)-(a + 1) + b;
+ return A >= MAX_LONGWORD ? MIN_LONGWORD : -(longword)A - 1;
+ }
+}
+
+static unsigned char const bitoff[ 256 ] = {
+ 8, 7, 6, 6, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4,
+ 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
+ 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
+ 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
+ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+};
+
+word gsm_norm (longword a )
+/*
+ * the number of left shifts needed to normalize the 32 bit
+ * variable L_var1 for positive values on the interval
+ *
+ * with minimum of
+ * minimum of 1073741824 (01000000000000000000000000000000) and
+ * maximum of 2147483647 (01111111111111111111111111111111)
+ *
+ *
+ * and for negative values on the interval with
+ * minimum of -2147483648 (-10000000000000000000000000000000) and
+ * maximum of -1073741824 ( -1000000000000000000000000000000).
+ *
+ * in order to normalize the result, the following
+ * operation must be done: L_norm_var1 = L_var1 << norm( L_var1 );
+ *
+ * (That's 'ffs', only from the left, not the right..)
+ */
+{
+ assert(a != 0);
+
+ if (a < 0) {
+ if (a <= -1073741824) return 0;
+ a = ~a;
+ }
+
+ return a & 0xffff0000
+ ? ( a & 0xff000000
+ ? -1 + bitoff[ 0xFF & (a >> 24) ]
+ : 7 + bitoff[ 0xFF & (a >> 16) ] )
+ : ( a & 0xff00
+ ? 15 + bitoff[ 0xFF & (a >> 8) ]
+ : 23 + bitoff[ 0xFF & a ] );
+}
+
+longword gsm_L_asl (longword a, int n)
+{
+ if (n >= 32) return 0;
+ if (n <= -32) return -(a < 0);
+ if (n < 0) return gsm_L_asr(a, -n);
+ return a << n;
+}
+
+word gsm_asr (word a, int n)
+{
+ if (n >= 16) return -(a < 0);
+ if (n <= -16) return 0;
+ if (n < 0) return a << -n;
+
+ return SASR_W (a, (word) n);
+}
+
+word gsm_asl (word a, int n)
+{
+ if (n >= 16) return 0;
+ if (n <= -16) return -(a < 0);
+ if (n < 0) return gsm_asr(a, -n);
+ return a << n;
+}
+
+longword gsm_L_asr (longword a, int n)
+{
+ if (n >= 32) return -(a < 0);
+ if (n <= -32) return 0;
+ if (n < 0) return a << -n;
+
+ return SASR_L (a, (word) n);
+}
+
+/*
+** word gsm_asr (word a, int n)
+** {
+** if (n >= 16) return -(a < 0);
+** if (n <= -16) return 0;
+** if (n < 0) return a << -n;
+**
+** # ifdef SASR_W
+** return a >> n;
+** # else
+** if (a >= 0) return a >> n;
+** else return -(word)( -(uword)a >> n );
+** # endif
+** }
+**
+*/
+/*
+ * (From p. 46, end of section 4.2.5)
+ *
+ * NOTE: The following lines gives [sic] one correct implementation
+ * of the div(num, denum) arithmetic operation. Compute div
+ * which is the integer division of num by denum: with denum
+ * >= num > 0
+ */
+
+word gsm_div (word num, word denum)
+{
+ longword L_num = num;
+ longword L_denum = denum;
+ word div = 0;
+ int k = 15;
+
+ /* The parameter num sometimes becomes zero.
+ * Although this is explicitly guarded against in 4.2.5,
+ * we assume that the result should then be zero as well.
+ */
+
+ /* assert(num != 0); */
+
+ assert(num >= 0 && denum >= num);
+ if (num == 0)
+ return 0;
+
+ while (k--) {
+ div <<= 1;
+ L_num <<= 1;
+
+ if (L_num >= L_denum) {
+ L_num -= L_denum;
+ div++;
+ }
+ }
+
+ return div;
+}
+
projects / Faustine.git / blobdiff