X-Git-Url: https://git.distorted.org.uk/~mdw/catacomb/blobdiff_plain/0fee61eb2ff1807c5f32a34499ef2753b6fcd9a5..HEAD:/symm/cfb-def.h

diff --git a/symm/cfb-def.h b/symm/cfb-def.h
index 8040d943..303bc9fd 100644
--- a/symm/cfb-def.h
+++ b/symm/cfb-def.h
@@ -59,6 +59,10 @@
 #  include "paranoia.h"
 #endif
 
+#ifndef CATACOMB_RSVR_H
+#  include "rsvr.h"
+#endif
+
 /*----- Macros ------------------------------------------------------------*/
 
 /* --- @CFB_DEF@ --- *
@@ -106,7 +110,7 @@ void pre##_cfbgetiv(const pre##_cfbctx *ctx, void *iv)			\
  */									\
 									\
 void pre##_cfbsetiv(pre##_cfbctx *ctx, const void *iv)			\
-  { memcpy(ctx->b, iv, PRE##_BLKSZ); ctx->off = PRE##_BLKSZ; }		\
+  { memcpy(ctx->b, iv, PRE##_BLKSZ); ctx->off = 0; }			\
 									\
 /* --- @pre_cfbbdry@ --- *						\
  *									\
@@ -125,7 +129,7 @@ void pre##_cfbbdry(pre##_cfbctx *ctx)					\
   BLKC_LOAD(PRE, t, ctx->b);						\
   pre##_eblk(&ctx->ctx, t, t);						\
   BLKC_STORE(PRE, ctx->b, t);						\
-  ctx->off = PRE##_BLKSZ;						\
+  ctx->off = 0;								\
   BURN(t);								\
 }									\
 									\
@@ -140,7 +144,7 @@ void pre##_cfbbdry(pre##_cfbctx *ctx)					\
  */									\
 									\
 void pre##_cfbsetkey(pre##_cfbctx *ctx, const pre##_ctx *k)		\
-  { ctx->ctx = *k; ctx->off = PRE##_BLKSZ; }				\
+  { ctx->ctx = *k; ctx->off = 0; }					\
 									\
 /* --- @pre_cfbinit@ --- *						\
  *									\
@@ -182,64 +186,75 @@ void pre##_cfbinit(pre##_cfbctx *ctx,					\
  *		sensitive to block boundaries.				\
  */									\
 									\
+static const rsvr_policy pre##_cfbpolicy = { 0, PRE##_BLKSZ, PRE##_BLKSZ }; \
+									\
 void pre##_cfbencrypt(pre##_cfbctx *ctx,				\
 		      const void *src, void *dest,			\
 		      size_t sz)					\
 {									\
+  rsvr_plan plan;							\
   const octet *s = src;							\
-  octet *d = dest;							\
-  unsigned off = ctx->off;						\
+  octet *d = dest, *p;							\
   uint32 t[PRE##_BLKSZ/4];						\
   octet y;								\
 									\
-  /* --- Empty blocks are trivial --- */				\
-									\
-  if (!sz) return;							\
-									\
-  /* --- If I can deal with the block from my buffer, do that --- */	\
-									\
-  if (sz < PRE##_BLKSZ - off) goto small;				\
-									\
-  /* --- Finish off what's left in my buffer --- */			\
-									\
-  while (off < PRE##_BLKSZ) {						\
-    y = s ? *s++ : 0;							\
-    ctx->b[off] ^= y;							\
-    if (d) *d++ = ctx->b[off];						\
-    off++; sz--;							\
-  }									\
-									\
-  /* --- Main encryption loop --- */					\
-									\
+  /* Construct a plan and prepare to follow through. */			\
+  rsvr_mkplan(&plan, &pre##_cfbpolicy, ctx->off, sz);			\
   BLKC_LOAD(PRE, t, ctx->b);						\
 									\
-  for (;;) {								\
-    pre##_eblk(&ctx->ctx, t, t);					\
-    if (sz < PRE##_BLKSZ) break;					\
-    if (s) { BLKC_XLOAD(PRE, t, s); s += PRE##_BLKSZ; }			\
-    if (d) { BLKC_STORE(PRE, d, t); d += PRE##_BLKSZ; }			\
-    sz -= PRE##_BLKSZ;							\
+  /* Initial portion, fulfilled from the buffer.  If the chunk is small	\
+   * enough, then this will be the only portion.  If the buffer is	\
+   * currently empty, then we must prepare it.				\
+   */									\
+  if (plan.head) {							\
+    if (!ctx->off) {							\
+      pre##_eblk(&ctx->ctx, t, t);					\
+      BLKC_STORE(PRE, ctx->b, t);					\
+    }									\
+    p = ctx->b + ctx->off; ctx->off += plan.head;			\
+    if (s) while (plan.head--) { y = *s++ ^ *p; *p++ = y; if (d) *d++ = y; } \
+    else if (d) { memcpy(d, p, plan.head); d += plan.head; }		\
+    BLKC_LOAD(PRE, t, ctx->b);						\
   }									\
 									\
-  BLKC_STORE(PRE, ctx->b, t);						\
-  off = 0;								\
-									\
-  /* --- Tidying up the tail end --- */					\
-									\
-  if (sz) {								\
-  small:								\
-    do {								\
-      y = s ? *s++ : 0;							\
-      ctx->b[off] ^= y;							\
-      if (d) *d++ = ctx->b[off];					\
-      off++; sz--;							\
-    } while (sz);							\
+  /* If the buffer is all used, then reset it ready for next time. */	\
+  ctx->off -= plan.from_rsvr;						\
+									\
+  /* Handle multiple whole blocks. */					\
+  if (!d) {								\
+    if (!s) while (plan.from_input) {					\
+      pre##_eblk(&ctx->ctx, t, t);					\
+      plan.from_input -= PRE##_BLKSZ;					\
+    } else while (plan.from_input) {					\
+      pre##_eblk(&ctx->ctx, t, t);					\
+      BLKC_XLOAD(PRE, t, s); s += PRE##_BLKSZ;				\
+      plan.from_input -= PRE##_BLKSZ;					\
+    }									\
+  } else {								\
+    if (!s) while (plan.from_input) {					\
+      pre##_eblk(&ctx->ctx, t, t);					\
+      BLKC_STORE(PRE, d, t); d += PRE##_BLKSZ;				\
+      plan.from_input -= PRE##_BLKSZ;					\
+    } else while (plan.from_input) {					\
+      pre##_eblk(&ctx->ctx, t, t);					\
+      BLKC_XLOAD(PRE, t, s); s += PRE##_BLKSZ;				\
+      BLKC_STORE(PRE, d, t); d += PRE##_BLKSZ;				\
+      plan.from_input -= PRE##_BLKSZ;					\
+    }									\
   }									\
 									\
-  /* --- Done --- */							\
-									\
-  ctx->off = off;							\
-  return;								\
+  /* Final portion.  Note that the buffer must be empty if there is a	\
+   * tail, since otherwise the input data would have been part of the	\
+   * head portion instad. */						\
+  if (!plan.tail)							\
+    BLKC_STORE(PRE, ctx->b, t);						\
+  else {								\
+    pre##_eblk(&ctx->ctx, t, t);					\
+    BLKC_STORE(PRE, ctx->b, t);						\
+    p = ctx->b; ctx->off += plan.tail;					\
+    if (s) while (plan.tail--) { y = *s++ ^ *p; *p++ = y; if (d) *d++ = y; } \
+    else if (d) { memcpy(d, p, plan.tail); d += plan.tail; }		\
+  }									\
 }									\
 									\
 /* --- @pre_cfbdecrypt@ --- *						\
@@ -260,53 +275,55 @@ void pre##_cfbdecrypt(pre##_cfbctx *ctx,				\
 		      const void *src, void *dest,			\
 		      size_t sz)					\
 {									\
+  rsvr_plan plan;							\
   const octet *s = src;							\
-  octet *d = dest;							\
-  unsigned off = ctx->off;						\
+  octet *d = dest, *p;							\
   uint32 t[PRE##_BLKSZ/4], u[PRE##_BLKSZ/4];				\
   octet y;								\
 									\
-  /* --- Empty blocks are trivial --- */				\
-									\
-  if (!sz) return;							\
-									\
-  /* --- If I can deal with the block from my buffer, do that --- */	\
-									\
-  if (sz < PRE##_BLKSZ - off) goto small;				\
-									\
-  /* --- Finish off what's left in my buffer --- */			\
-									\
-  while (off < PRE##_BLKSZ)						\
-    { y = *s++; *d++ = ctx->b[off] ^ y; ctx->b[off++] = y; sz--; }	\
+  /* Construct a plan and prepare to follow through. */			\
+  rsvr_mkplan(&plan, &pre##_cfbpolicy, ctx->off, sz);			\
+  BLKC_LOAD(PRE, t, ctx->b);						\
 									\
-  /* --- Main encryption loop --- */					\
+  /* Initial portion, fulfilled from the buffer.  If the chunk is small	\
+   * enough, then this will be the only portion.  If the buffer is	\
+   * currently empty, then we must prepare it.				\
+   */									\
+  if (plan.head) {							\
+    if (!ctx->off) {							\
+      pre##_eblk(&ctx->ctx, t, t);					\
+      BLKC_STORE(PRE, ctx->b, t);					\
+    }									\
+    p = ctx->b + ctx->off;						\
+    ctx->off += plan.head;						\
+    while (plan.head--) { y = *s++; *d++ = y ^ *p; *p++ = y; }		\
+    BLKC_LOAD(PRE, t, ctx->b);						\
+  }									\
 									\
-  BLKC_LOAD(PRE, t, ctx->b);						\
+  /* If the buffer is all used, then reset it ready for next time. */	\
+  ctx->off -= plan.from_rsvr;						\
 									\
-  for (;;) {								\
+  /* Handle multiple whole blocks. */					\
+  while (plan.from_input) {						\
     pre##_eblk(&ctx->ctx, t, t);					\
-    if (sz < PRE##_BLKSZ) break;					\
     BLKC_LOAD(PRE, u, s); s += PRE##_BLKSZ;				\
     BLKC_XSTORE(PRE, d, t, u); d += PRE##_BLKSZ;			\
     BLKC_MOVE(PRE, t, u);						\
-    sz -= PRE##_BLKSZ;							\
+    plan.from_input -= PRE##_BLKSZ;					\
   }									\
 									\
-  BLKC_STORE(PRE, ctx->b, t);						\
-  off = 0;								\
-									\
-  /* --- Tidying up the tail end --- */					\
-									\
-  if (sz) {								\
-  small:								\
-    do { y = *s++; *d++ = ctx->b[off] ^ y; ctx->b[off++] = y; sz--; }	\
-    while (sz);								\
+  /* Final portion.  Note that the buffer must be empty if there is a	\
+   * tail, since otherwise the input data would have been part of the	\
+   * head portion instad. */						\
+  if (!plan.tail)							\
+    BLKC_STORE(PRE, ctx->b, t);						\
+  else {								\
+    pre##_eblk(&ctx->ctx, t, t);					\
+    BLKC_STORE(PRE, ctx->b, t);						\
+    p = ctx->b;								\
+    ctx->off += plan.tail;						\
+    while (plan.tail--) { y = *s++; *d++ = y ^ *p; *p++ = y; }		\
   }									\
-									\
-  /* --- Done --- */							\
-									\
-  ctx->off = off;							\
-  return;								\
 }									\
 									\
 /* --- Generic cipher interface --- */					\