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[13.113.80.70]) by smtp.gmail.com with ESMTPSA id o13-20020a170902d4cd00b0015e8d4eb2aesm10234887plg.248.2022.06.06.03.19.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 06 Jun 2022 03:19:24 -0700 (PDT) From: Zhang Boyang To: linux-kernel@vger.kernel.org Cc: ferdinand.blomqvist@gmail.com, tglx@linutronix.de, Zhang Boyang Subject: [PATCH 1/2] rslib: Replace hard-coded 1 with alpha_to[0] Date: Mon, 6 Jun 2022 18:19:00 +0800 Message-Id: <20220606101901.83538-1-zhangboyang.id@gmail.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220605073857.126497-1-zhangboyang.id@gmail.com> References: <20220605073857.126497-1-zhangboyang.id@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently the rslib allows customizing the finite field by the `gffunc' parameter of init_rs_non_canonical(). However, there are several places in rslib use hard-coded 1 instead of alpha_to[0], leading to errors if gffunc(0) != 1. This patch fixes the problem. One of such `gffunc' might be gffunc'(x) = swab16(gffunc(swab16(x))), as gffunc'(0) = swab16(1). This special gffunc'(x) is useful when implementing RS coder for 16 bit foreign-endian symbols. Signed-off-by: Zhang Boyang --- lib/reed_solomon/decode_rs.c | 4 ++-- lib/reed_solomon/reed_solomon.c | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/lib/reed_solomon/decode_rs.c b/lib/reed_solomon/decode_rs.c index 805de84ae83d..6c1d53d1b702 100644 --- a/lib/reed_solomon/decode_rs.c +++ b/lib/reed_solomon/decode_rs.c @@ -104,7 +104,7 @@ decode: memset(&lambda[1], 0, nroots * sizeof(lambda[0])); - lambda[0] = 1; + lambda[0] = alpha_to[0]; if (no_eras > 0) { /* Init lambda to be the erasure locator polynomial */ @@ -198,7 +198,7 @@ memcpy(®[1], &lambda[1], nroots * sizeof(reg[0])); count = 0; /* Number of roots of lambda(x) */ for (i = 1, k = iprim - 1; i <= nn; i++, k = rs_modnn(rs, k + iprim)) { - q = 1; /* lambda[0] is always 0 */ + q = alpha_to[0]; /* lambda[0] is always 0 */ for (j = deg_lambda; j > 0; j--) { if (reg[j] != nn) { reg[j] = rs_modnn(rs, reg[j] + j); diff --git a/lib/reed_solomon/reed_solomon.c b/lib/reed_solomon/reed_solomon.c index bbc01bad3053..bb4f44c8edba 100644 --- a/lib/reed_solomon/reed_solomon.c +++ b/lib/reed_solomon/reed_solomon.c @@ -131,9 +131,9 @@ static struct rs_codec *codec_init(int symsize, int gfpoly, int (*gffunc)(int), rs->iprim = iprim / prim; /* Form RS code generator polynomial from its roots */ - rs->genpoly[0] = 1; + rs->genpoly[0] = rs->alpha_to[0]; for (i = 0, root = fcr * prim; i < nroots; i++, root += prim) { - rs->genpoly[i + 1] = 1; + rs->genpoly[i + 1] = rs->alpha_to[0]; /* Multiply rs->genpoly[] by @**(root + x) */ for (j = i; j > 0; j--) { if (rs->genpoly[j] != 0) { -- 2.30.2