altos: Add 64-bit subtraction

Signed-off-by: Keith Packard <keithp@keithp.com>

3 files changed, 17 insertions, 0 deletions

diff --git a/src/core/ao_int64.c b/src/core/ao_int64.c
index 5307342d..07cdb357 100644
--- a/src/core/ao_int64.c
+++ b/src/core/ao_int64.c
@@ -27,6 +27,17 @@ void ao_plus64(ao_int64_t *r, ao_int64_t *a, ao_int64_t *b) {
 	r->low = t;
 }
 
+void ao_minus64(ao_int64_t *r, ao_int64_t *a, ao_int64_t *b) {
+	uint32_t	t;
+
+
+	r->high = a->high - b->high;
+	t = a->low - b->low;
+	if (t > a->low)
+		r->high--;
+	r->low = t;
+}
+
 void ao_rshift64(ao_int64_t *r, ao_int64_t *a, uint8_t d) {
 	if (d < 32) {
 		r->low = a->low >> d;
diff --git a/src/core/ao_int64.h b/src/core/ao_int64.h
index e5eee823..cf12f0d8 100644
--- a/src/core/ao_int64.h
+++ b/src/core/ao_int64.h
@@ -26,6 +26,7 @@ typedef struct {
 } ao_int64_t;
 
 void ao_plus64(ao_int64_t *r, ao_int64_t *a, ao_int64_t *b);
+void ao_minus64(ao_int64_t *r, ao_int64_t *a, ao_int64_t *b);
 void ao_neg64(ao_int64_t *r, ao_int64_t *a);
 void ao_lshift64_16(ao_int64_t *r, uint16_t a, uint8_t d);
 void ao_rshift64(ao_int64_t *r, ao_int64_t *a, uint8_t d);
@@ -33,6 +34,7 @@ void ao_lshift64(ao_int64_t *r, ao_int64_t *a, uint8_t d);
 void ao_mul64_64_64(ao_int64_t *r, ao_int64_t *a, ao_int64_t *b);
 void ao_mul64_32_32(ao_int64_t *r, int32_t a, int32_t b);
 void ao_mul64_64_16(ao_int64_t *r, ao_int64_t *a, uint16_t b);
+void ao_mul64(ao_int64_t *r, ao_int64_t *a, ao_int64_t *b);
 
 #define ao_int64_init32(r, a) (((r)->high = 0), (r)->low = (a))
 #define ao_int64_init64(r, a, b) (((r)->high = (a)), (r)->low = (b))
diff --git a/src/test/ao_int64_test.c b/src/test/ao_int64_test.c
index 4c88b1a1..c26a63b0 100644
--- a/src/test/ao_int64_test.c
+++ b/src/test/ao_int64_test.c
@@ -65,6 +65,10 @@ do_test(int trial, int64_t a, int64_t b)
 	test_a(+, ao_plus64, a, b, &ao_a, &ao_b);
 	test_b(+, ao_plus64, a, b, &ao_a, &ao_b);
 	test_x(+, ao_plus64, a, b, &ao_a, &ao_b);
+	test(-, ao_minus64, a, b, &ao_a, &ao_b);
+	test_a(-, ao_minus64, a, b, &ao_a, &ao_b);
+	test_b(-, ao_minus64, a, b, &ao_a, &ao_b);
+	test_x(-, ao_minus64, a, b, &ao_a, &ao_b);
 	test(*, ao_mul64_32_32,(int64_t) (int32_t) a, (int32_t) b, (int32_t) a, (int32_t) b);
 	test(*, ao_mul64, a, b, &ao_a, &ao_b);
 	test_a(*, ao_mul64, a, b, &ao_a, &ao_b);