commit 30f073236922fe4e528fdf82eb442babb50516fa
author Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com> Wed Aug 13 08:42:45 2025 +0200
committer Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com> Wed Aug 13 09:01:55 2025 +0200
tree 717a3a207201bc8d2c0b5f773049fc7cfba2dea2
parent 87e77d6516c6161e6cfe3043fefa22e62d32c885

bignum: gcd: improve comments

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>

library/bignum.c

diff --git a/library/bignum.c b/library/bignum.c
index 3587148..d03e26c 100644
--- a/library/bignum.c
+++ b/library/bignum.c
@@ -1849,9 +1849,9 @@
         goto cleanup;
     }
 
+    /* Make boths inputs odd by putting powers of 2 on the side */
     const size_t za = mbedtls_mpi_lsb(&TA);
     const size_t zb = mbedtls_mpi_lsb(&TB);
-
     MBEDTLS_MPI_CHK(mbedtls_mpi_shift_r(&TA, za));
     MBEDTLS_MPI_CHK(mbedtls_mpi_shift_r(&TB, zb));
 
@@ -1861,6 +1861,7 @@
 
     MBEDTLS_MPI_CHK(mbedtls_mpi_gcd_modinv_odd(G, NULL, &TA, &TB));
 
+    /* Re-inject the power of 2 we had previously put aside */
     size_t zg = za > zb ? zb : za; // zg = min(za, zb)
     MBEDTLS_MPI_CHK(mbedtls_mpi_shift_l(G, zg));