libbb/sha: improve comments

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

4 files changed, 20 insertions, 21 deletions

diff --git a/libbb/hash_md5_sha256_x86-32_shaNI.S b/libbb/hash_md5_sha256_x86-32_shaNI.S
index 413e2df9e..4b33449d4 100644
--- a/libbb/hash_md5_sha256_x86-32_shaNI.S
+++ b/libbb/hash_md5_sha256_x86-32_shaNI.S
@@ -4,7 +4,7 @@
 // We use shorter insns, even though they are for "wrong"
 // data type (fp, not int).
 // For Intel, there is no penalty for doing it at all
-// (CPUs which do have such penalty do not support SHA1 insns).
+// (CPUs which do have such penalty do not support SHA insns).
 // For AMD, the penalty is one extra cycle
 // (allegedly: I failed to find measurable difference).
 
@@ -39,12 +39,13 @@
         .balign 8       # allow decoders to fetch at least 2 first insns
 sha256_process_block64_shaNI:
 
-        movu128         76+0*16(%eax), XMMTMP /* DCBA (msb-to-lsb: 3,2,1,0) */
-        movu128         76+1*16(%eax), STATE1 /* HGFE */
+        movu128         76+0*16(%eax), XMMTMP /* ABCD (little-endian dword order) */
+        movu128         76+1*16(%eax), STATE1 /* EFGH */
 /* shufps takes dwords 0,1 from *2nd* operand, and dwords 2,3 from 1st one */
         mova128         STATE1, STATE0
-        shufps          SHUF(1,0,1,0), XMMTMP, STATE0 /* ABEF */
-        shufps          SHUF(3,2,3,2), XMMTMP, STATE1 /* CDGH */
+        /* ---          -------------- ABCD -- EFGH */
+        shufps          SHUF(1,0,1,0), XMMTMP, STATE0 /* FEBA */
+        shufps          SHUF(3,2,3,2), XMMTMP, STATE1 /* HGDC */
 
 /* XMMTMP holds flip mask from here... */
         mova128         PSHUFFLE_BSWAP32_FLIP_MASK, XMMTMP
@@ -232,12 +233,11 @@ sha256_process_block64_shaNI:
                 sha256rnds2     STATE1, STATE0
 
         /* Write hash values back in the correct order */
-        /* STATE0: ABEF (msb-to-lsb: 3,2,1,0) */
-        /* STATE1: CDGH */
         mova128         STATE0, XMMTMP
 /* shufps takes dwords 0,1 from *2nd* operand, and dwords 2,3 from 1st one */
-        shufps          SHUF(3,2,3,2), STATE1, STATE0 /* DCBA */
-        shufps          SHUF(1,0,1,0), STATE1, XMMTMP /* HGFE */
+        /* ---          -------------- HGDC -- FEBA */
+        shufps          SHUF(3,2,3,2), STATE1, STATE0 /* ABCD */
+        shufps          SHUF(1,0,1,0), STATE1, XMMTMP /* EFGH */
         /* add current hash values to previous ones */
         movu128         76+1*16(%eax), STATE1
         paddd           XMMTMP, STATE1
diff --git a/libbb/hash_md5_sha256_x86-64_shaNI.S b/libbb/hash_md5_sha256_x86-64_shaNI.S
index c246762aa..5ed80c2ef 100644
--- a/libbb/hash_md5_sha256_x86-64_shaNI.S
+++ b/libbb/hash_md5_sha256_x86-64_shaNI.S
@@ -4,7 +4,7 @@
 // We use shorter insns, even though they are for "wrong"
 // data type (fp, not int).
 // For Intel, there is no penalty for doing it at all
-// (CPUs which do have such penalty do not support SHA1 insns).
+// (CPUs which do have such penalty do not support SHA insns).
 // For AMD, the penalty is one extra cycle
 // (allegedly: I failed to find measurable difference).
 
@@ -42,12 +42,13 @@
         .balign 8       # allow decoders to fetch at least 2 first insns
 sha256_process_block64_shaNI:
 
-        movu128         80+0*16(%rdi), XMMTMP /* DCBA (msb-to-lsb: 3,2,1,0) */
-        movu128         80+1*16(%rdi), STATE1 /* HGFE */
+        movu128         80+0*16(%rdi), XMMTMP /* ABCD (little-endian dword order) */
+        movu128         80+1*16(%rdi), STATE1 /* EFGH */
 /* shufps takes dwords 0,1 from *2nd* operand, and dwords 2,3 from 1st one */
         mova128         STATE1, STATE0
-        shufps          SHUF(1,0,1,0), XMMTMP, STATE0 /* ABEF */
-        shufps          SHUF(3,2,3,2), XMMTMP, STATE1 /* CDGH */
+        /* ---          -------------- ABCD -- EFGH */
+        shufps          SHUF(1,0,1,0), XMMTMP, STATE0 /* FEBA */
+        shufps          SHUF(3,2,3,2), XMMTMP, STATE1 /* HGDC */
 
 /* XMMTMP holds flip mask from here... */
         mova128         PSHUFFLE_BSWAP32_FLIP_MASK(%rip), XMMTMP
@@ -243,13 +244,11 @@ sha256_process_block64_shaNI:
         paddd           CDGH_SAVE, STATE1
 
         /* Write hash values back in the correct order */
-        /* STATE0: ABEF (msb-to-lsb: 3,2,1,0) */
-        /* STATE1: CDGH */
         mova128         STATE0, XMMTMP
 /* shufps takes dwords 0,1 from *2nd* operand, and dwords 2,3 from 1st one */
-        shufps          SHUF(3,2,3,2), STATE1, STATE0 /* DCBA */
-        shufps          SHUF(1,0,1,0), STATE1, XMMTMP /* HGFE */
-
+        /* ---          -------------- HGDC -- FEBA */
+        shufps          SHUF(3,2,3,2), STATE1, STATE0 /* ABCD */
+        shufps          SHUF(1,0,1,0), STATE1, XMMTMP /* EFGH */
         movu128         STATE0, 80+0*16(%rdi)
         movu128         XMMTMP, 80+1*16(%rdi)
 
diff --git a/libbb/hash_md5_sha_x86-32_shaNI.S b/libbb/hash_md5_sha_x86-32_shaNI.S
index afca98a62..c7fb243ce 100644
--- a/libbb/hash_md5_sha_x86-32_shaNI.S
+++ b/libbb/hash_md5_sha_x86-32_shaNI.S
@@ -4,7 +4,7 @@
 // We use shorter insns, even though they are for "wrong"
 // data type (fp, not int).
 // For Intel, there is no penalty for doing it at all
-// (CPUs which do have such penalty do not support SHA1 insns).
+// (CPUs which do have such penalty do not support SHA insns).
 // For AMD, the penalty is one extra cycle
 // (allegedly: I failed to find measurable difference).
 
diff --git a/libbb/hash_md5_sha_x86-64_shaNI.S b/libbb/hash_md5_sha_x86-64_shaNI.S
index 54d122788..c13cdec07 100644
--- a/libbb/hash_md5_sha_x86-64_shaNI.S
+++ b/libbb/hash_md5_sha_x86-64_shaNI.S
@@ -4,7 +4,7 @@
 // We use shorter insns, even though they are for "wrong"
 // data type (fp, not int).
 // For Intel, there is no penalty for doing it at all
-// (CPUs which do have such penalty do not support SHA1 insns).
+// (CPUs which do have such penalty do not support SHA insns).
 // For AMD, the penalty is one extra cycle
 // (allegedly: I failed to find measurable difference).