From: lkcl <lkcl@web>
Date: Mon, 28 Dec 2020 16:31:00 +0000 (+0000)
Subject: (no commit message)
X-Git-Tag: convert-csv-opcode-to-binary~758
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=44e0e3f333353436e3b3f856dc4b87aa187bcd10;p=libreriscv.git

---

diff --git a/openpower/sv/bitmanip.mdwn b/openpower/sv/bitmanip.mdwn
index 73ba2ba15..21eebc708 100644
--- a/openpower/sv/bitmanip.mdwn
+++ b/openpower/sv/bitmanip.mdwn
@@ -230,3 +230,22 @@ for (int i = 0; i < XLEN; i++)
 if ((rs2 >> i) & 1)
 x ^= rs1 >> (XLEN-i-1); return x;
 ```
+
+# crc
+
+```
+uint_xlen_t crc32(uint_xlen_t x, int nbits) { for (int i = 0; i < nbits; i++)
+}
+x = (x >> 1) ^ (0xEDB88320 & ~((x&1)-1)); return x;
+uint_xlen_t crc32c(uint_xlen_t x, int nbits) { for (int i = 0; i < nbits; i++)
+}
+x = (x >> 1) ^ (0x82F63B78 & ~((x&1)-1)); return x;
+uint_xlen_t crc32_b(uint_xlen_t rs1) { return crc32(rs1, 8); } uint_xlen_t crc32_h(uint_xlen_t rs1) { return crc32(rs1, 16); } uint_xlen_t crc32_w(uint_xlen_t rs1) { return crc32(rs1, 32); }
+uint_xlen_t crc32c_b(uint_xlen_t rs1) { return crc32c(rs1, 8); } uint_xlen_t crc32c_h(uint_xlen_t rs1) { return crc32c(rs1, 16); } uint_xlen_t crc32c_w(uint_xlen_t rs1) { return crc32c(rs1, 32); }
+#if XLEN > 32
+uint_xlen_t crc32_d (uint_xlen_t rs1) { return crc32 (rs1, 64); } uint_xlen_t crc32c_d(uint_xlen_t rs1) { return crc32c(rs1, 64); } #endif
+Payload data must be XOR’ed into the LSB end of the state before executing the CRC instruction. The following code demonstrates the use of crc32.b:
+uint32_t crc32_demo(const uint8_t *p, int len) { uint32_t x = 0xffffffff;
+for (int i = 0; i < len; i++) { x = x ^ p[i];
+x = crc32_b(x); } }return ~x;
+```