diff --git a/femtolisp/builtins.c b/femtolisp/builtins.c
index fdd14e9..4931ac4 100644
--- a/femtolisp/builtins.c
+++ b/femtolisp/builtins.c
@@ -332,7 +332,6 @@ value_t fl_rand32(value_t *args, u_int32_t nargs)
 #ifdef BITS64
     return fixnum(r);
 #else
-    if (fits_fixnum(r)) return fixnum(r);
     return mk_uint32(r);
 #endif
 }
@@ -340,9 +339,6 @@ value_t fl_rand64(value_t *args, u_int32_t nargs)
 {
     (void)args; (void)nargs;
     ulong r = (((uint64_t)random())<<32) | random();
-#ifdef BITS64
-    if (fits_fixnum(r)) return fixnum(r);
-#endif
     return mk_uint64(r);
 }
 value_t fl_randd(value_t *args, u_int32_t nargs)
diff --git a/femtolisp/cvalues.c b/femtolisp/cvalues.c
index f2b2b12..4b18502 100644
--- a/femtolisp/cvalues.c
+++ b/femtolisp/cvalues.c
@@ -16,7 +16,7 @@ static int struct_aligns[8] = {
     sizeof(struct { char a; int64_t i; }) };
 static int ALIGN2, ALIGN4, ALIGN8, ALIGNPTR;
 
-typedef void (*cvinitfunc_t)(value_t*, u_int32_t, void*, void*);
+typedef void (*cvinitfunc_t)(value_t, value_t, void*, void*);
 
 value_t int8sym, uint8sym, int16sym, uint16sym, int32sym, uint32sym;
 value_t int64sym, uint64sym;
@@ -30,7 +30,7 @@ value_t unionsym;
 
 value_t autoreleasesym, typeofsym, sizeofsym;
 
-static void cvalue_init(value_t type, value_t *vs, u_int32_t nv, void *dest);
+static void cvalue_init(value_t type, value_t v, void *dest);
 
 void cvalue_print(ios_t *f, value_t v, int princ);
 // exported guest functions
@@ -239,39 +239,45 @@ static double strtodouble(char *str, char *fname)
 }
 
 #define num_ctor(typenam, cnvt, tag, fromstr)                           \
-static void cvalue_##typenam##_init(value_t *args, u_int32_t nargs,     \
+static void cvalue_##typenam##_init(value_t type, value_t arg,          \
                                     void *dest, void *data)             \
 {                                                                       \
     typenam##_t n=0;                                                    \
-    (void)data;                                                         \
-    if (nargs) {                                                        \
-        if (iscvalue(args[0])) {                                        \
-            cvalue_t *cv = (cvalue_t*)ptr(args[0]);                     \
-            void *p = cv_data(cv);                                      \
-            if (valid_numtype(cv_numtype(cv))) {                        \
-                n = (typenam##_t)conv_to_##cnvt(p, cv_numtype(cv));     \
-            }                                                           \
-            else if (cv->flags.cstring) {                               \
-                n = fromstr(p, #typenam);                               \
-            }                                                           \
-            else if (cv_len(cv) == sizeof(typenam##_t)) {               \
-                n = *(typenam##_t*)p;                                   \
-            }                                                           \
-            else {                                                      \
-                type_error(#typenam, "number", args[0]);                \
-            }                                                           \
+    (void)data; (void)type;                                             \
+    if (isfixnum(arg)) {                                                \
+        n = numval(arg);                                                \
+    }                                                                   \
+    else if (iscvalue(arg)) {                                           \
+        cvalue_t *cv = (cvalue_t*)ptr(arg);                             \
+        void *p = cv_data(cv);                                          \
+        if (valid_numtype(cv_numtype(cv))) {                            \
+            n = (typenam##_t)conv_to_##cnvt(p, cv_numtype(cv));         \
+        }                                                               \
+        else if (cv->flags.cstring) {                                   \
+            n = fromstr(p, #typenam);                                   \
+        }                                                               \
+        else if (cv_len(cv) == sizeof(typenam##_t)) {                   \
+            n = *(typenam##_t*)p;                                       \
         }                                                               \
         else {                                                          \
-            n = tofixnum(args[0], #typenam);                            \
+            goto cnvt_error;                                            \
         }                                                               \
     }                                                                   \
+    else {                                                              \
+        goto cnvt_error;                                                \
+    }                                                                   \
     *((typenam##_t*)dest) = n;                                          \
+    return;                                                             \
+ cnvt_error:                                                            \
+    type_error(#typenam, "number", arg);                                \
 }                                                                       \
 value_t cvalue_##typenam(value_t *args, u_int32_t nargs)                \
 {                                                                       \
+    if (nargs==0) { PUSH(fixnum(0)); args = &Stack[SP-1]; }             \
     value_t cv = cvalue(typenam##sym, sizeof(typenam##_t));             \
     ((cprim_t*)ptr(cv))->flags.numtype = tag;                           \
-    cvalue_##typenam##_init(args, nargs, &((cprim_t*)ptr(cv))->data, 0); \
+    cvalue_##typenam##_init(typenam##sym,                               \
+                            args[0], &((cprim_t*)ptr(cv))->data, 0);    \
     return cv;                                                          \
 }                                                                       \
 value_t mk_##typenam(typenam##_t n)                                     \
@@ -332,20 +338,18 @@ value_t char_from_code(uint32_t code)
     return cvalue_char(&ccode, 1);
 }
 
-static void cvalue_enum_init(value_t *args, u_int32_t nargs, void *dest,
-                             void *data)
+static void cvalue_enum_init(value_t type, value_t arg, void *dest, void *data)
 {
     int n=0;
     value_t syms;
 
     (void)data;
-    argcount("enum", nargs, 2);
-    syms = args[0];
+    syms = car(cdr(type));
     if (!iscons(syms))
         type_error("enum", "cons", syms);
-    if (issymbol(args[1])) {
+    if (issymbol(arg)) {
         while (iscons(syms)) {
-            if (car_(syms) == args[1]) {
+            if (car_(syms) == arg) {
                 *(int*)dest = n;
                 return;
             }
@@ -354,13 +358,13 @@ static void cvalue_enum_init(value_t *args, u_int32_t nargs, void *dest,
         }
         lerror(ArgError, "enum: invalid enum value");
     }
-    if (isfixnum(args[1])) {
-        n = (int)numval(args[1]);
+    if (isfixnum(arg)) {
+        n = (int)numval(arg);
     }
-    else if (iscvalue(args[1])) {
-        cvalue_t *cv = (cvalue_t*)ptr(args[1]);
+    else if (iscvalue(arg)) {
+        cvalue_t *cv = (cvalue_t*)ptr(arg);
         if (!valid_numtype(cv_numtype(cv)))
-            type_error("enum", "number", args[1]);
+            type_error("enum", "number", arg);
         n = conv_to_int32(cv_data(cv), cv_numtype(cv));
     }
     if ((unsigned)n >= llength(syms))
@@ -373,105 +377,112 @@ value_t cvalue_enum(value_t *args, u_int32_t nargs)
     argcount("enum", nargs, 2);
     value_t cv = cvalue(list2(enumsym, args[0]), 4);
     ((cvalue_t*)ptr(cv))->flags.numtype = T_INT32;
-    cvalue_enum_init(args, nargs, cv_data((cvalue_t*)ptr(cv)), NULL);
+    cvalue_enum_init(cv_type((cvalue_t*)ptr(cv)),
+                     args[1], cv_data((cvalue_t*)ptr(cv)), NULL);
     return cv;
 }
 
-static void cvalue_array_init(value_t *args, u_int32_t nargs, void *dest,
-                              void *data)
+static void array_init_fromargs(char *dest, value_t *vals, size_t cnt,
+                                value_t eltype, size_t elsize)
 {
-    size_t cnt=0, elsize, i;
-    value_t *init = NULL;
+    size_t i;
+    for(i=0; i < cnt; i++) {
+        cvalue_init(eltype, vals[i], dest);
+        dest += elsize;
+    }
+}
+
+static int isarray(value_t v)
+{
+    if (!iscvalue(v)) return 0;
+    value_t type = cv_type((cvalue_t*)ptr(v));
+    return (iscons(type) && car_(type)==arraysym);
+}
+
+static size_t predict_arraylen(value_t arg)
+{
+    if (isvector(arg))
+        return vector_size(arg);
+    else if (iscons(arg))
+        return llength(arg);
+    else if (arg == NIL)
+        return 0;
+    if (isarray(arg))
+        return cvalue_arraylen(arg);
+    return 1;
+}
+
+static void cvalue_array_init(value_t type, value_t arg, void *dest, void *data)
+{
+    size_t elsize, i, cnt, sz;
     int junk;
+    value_t eltype = car(cdr(type));
 
     if (data != 0)
         elsize = (size_t)data;  // already computed by constructor
     else
-        elsize = ctype_sizeof(args[0], &junk);
-    char *out = (char*)dest;
+        elsize = ctype_sizeof(eltype, &junk);
 
-    if (nargs == 2) {
-        if (isvector(args[1]) || iscons(args[1]) || args[1]==NIL)
-            init = &args[1];
-        else
-            cnt = toulong(args[1], "array");
+    cnt = predict_arraylen(arg);
+
+    if (iscons(cdr_(cdr_(type)))) {
+        size_t tc = toulong(car_(cdr_(cdr_(type))), "array");
+        if (tc != cnt)
+            lerror(ArgError, "array: size mismatch");
     }
-    else if (nargs == 3) {
-        cnt = toulong(args[1], "array");
-        init = &args[2];
+
+    sz = elsize * cnt;
+
+    if (isvector(arg)) {
+        array_init_fromargs((char*)dest, &vector_elt(arg,0), cnt,
+                            eltype, elsize);
+        return;
     }
-    else {
-        argcount("array", nargs, 2);
-    }
-    if (init) {
-        if (isvector(*init)) {
-            if (cnt && vector_size(*init) != cnt)
-                lerror(ArgError, "array: size mismatch");
-            cnt = vector_size(*init);
-            for(i=0; i < cnt; i++) {
-                cvalue_init(args[0], &vector_elt(*init, i), 1, out);
-                out += elsize;
-            }
-            return;
+    else if (iscons(arg) || arg==NIL) {
+        i = 0;
+        while (iscons(arg)) {
+            if (SP >= N_STACK)
+                break;
+            PUSH(car_(arg));
+            i++;
+            arg = cdr_(arg);
         }
-        else if (iscons(*init) || *init==NIL) {
-            for(i=0; i < cnt || cnt==0; i++) {
-                if (!iscons(*init)) {
-                    if (cnt != 0)
-                        lerror(ArgError, "array: size mismatch");
-                    else
-                        break;
-                }
-                cvalue_init(args[0], &car_(*init), 1, out);
-                out += elsize;
-                *init = cdr_(*init);
-            }
-            return;
-        }
-        else if (iscvalue(*init)) {
-            cvalue_t *cv = (cvalue_t*)ptr(*init);
-            size_t tot = cnt*elsize;
-            if (tot == cv_len(cv)) {
-                if (tot) memcpy(out, cv_data(cv), tot);
+        if (i != cnt)
+            lerror(ArgError, "array: size mismatch");
+        array_init_fromargs((char*)dest, &Stack[SP-i], i, eltype, elsize);
+        POPN(i);
+        return;
+    }
+    else if (iscvalue(arg)) {
+        cvalue_t *cv = (cvalue_t*)ptr(arg);
+        if (isarray(arg)) {
+            value_t aet = car(cdr(cv_type(cv)));
+            if (aet == eltype) {
+                if (cv_len(cv) == sz)
+                    memcpy(dest, cv_data(cv), sz);
+                else
+                    lerror(ArgError, "array: size mismatch");
                 return;
             }
+            else {
+                // TODO: initialize array from different type elements
+                lerror(ArgError, "array: element type mismatch");
+            }
         }
-        else {
-            type_error("array", "cons", *init);
-        }
-        lerror(ArgError, "array: invalid size");
     }
-}
-
-static size_t predict_arraylen(value_t *args, u_int32_t nargs, size_t *elsz)
-{
-    int junk;
-    size_t cnt;
-
-    if (nargs < 2)
-        argcount("array", nargs, 2);
-    *elsz = ctype_sizeof(args[0], &junk);
-    if (isvector(args[1])) {
-        cnt = vector_size(args[1]);
-    }
-    else if (iscons(args[1])) {
-        cnt = llength(args[1]);
-    }
-    else if (args[1] == NIL) {
-        cnt = 0;
-    }
-    else {
-        cnt = toulong(args[1], "array");
-    }
-    return cnt;
+    if (cnt == 1)
+        cvalue_init(eltype, arg, dest);
+    else
+        type_error("array", "sequence", arg);
 }
 
 static value_t alloc_array(value_t type, size_t sz)
 {
     value_t cv;
     if (car_(cdr_(type)) == charsym) {
+        PUSH(type);
         cv = cvalue_string(sz);
-        ((cvalue_t*)ptr(cv))->type = type;
+        ((cvalue_t*)ptr(cv))->type = POP();
     }
     else {
         cv = cvalue(type, sz);
@@ -482,12 +493,18 @@ static value_t alloc_array(value_t type, size_t sz)
 value_t cvalue_array(value_t *args, u_int32_t nargs)
 {
     size_t elsize, cnt, sz;
+    int junk;
 
-    cnt = predict_arraylen(args, nargs, &elsize);
+    if (nargs < 1)
+        argcount("array", nargs, 1);
+
+    cnt = nargs - 1;
+    elsize = ctype_sizeof(args[0], &junk);
     sz = elsize * cnt;
 
     value_t cv = alloc_array(listn(3, arraysym, args[0], size_wrap(cnt)), sz);
-    cvalue_array_init(args, nargs, cv_data((cvalue_t*)ptr(cv)), (void*)elsize);
+    array_init_fromargs(cv_data((cvalue_t*)ptr(cv)), &args[1], cnt,
+                        args[0], elsize);
     return cv;
 }
 
@@ -683,33 +700,24 @@ value_t cvalue_copy(value_t v)
     return tagptr(pnv, TAG_CVALUE);
 }
 
-static void cvalue_init(value_t type, value_t *vs, u_int32_t nv, void *dest)
+static void cvalue_init(value_t type, value_t v, void *dest)
 {
     cvinitfunc_t f;
-    unsigned int i, na=0;
 
     if (issymbol(type)) {
         f = ((symbol_t*)ptr(type))->dlcache;
     }
-    else if (!iscons(type)) {
-        f = NULL;
-        lerror(ArgError, "c-value: invalid c type");
-    }
-    else {
+    else if (iscons(type)) {
         value_t head = car_(type);
         f = ((symbol_t*)ptr(head))->dlcache;
-        type = cdr_(type);
-        while (iscons(type)) {
-            PUSH(car_(type));
-            na++;
-            type = cdr_(type);
-        }
     }
-    for(i=0; i < nv; i++)
-        PUSH(vs[i]);
-    na += nv;
-    f(&Stack[SP-na], na, dest, NULL);
-    POPN(na);
+    else {
+        f = NULL;
+    }
+    if (f == NULL)
+        lerror(ArgError, "c-value: invalid c type");
+
+    f(type, v, dest, NULL);
 }
 
 static numerictype_t sym_to_numtype(value_t type)
@@ -756,29 +764,26 @@ static numerictype_t sym_to_numtype(value_t type)
 // type, including user-defined.
 value_t cvalue_new(value_t *args, u_int32_t nargs)
 {
-    if (nargs < 1)
-        argcount("c-value", nargs, 1);
+    if (nargs < 1 || nargs > 2)
+        argcount("c-value", nargs, 2);
     value_t type = args[0];
     value_t cv;
     if (iscons(type) && car_(type) == arraysym) {
         // special case to handle incomplete array types bla[]
-        size_t elsz;
-        value_t c = cdr_(type);
-        int na=0;
-        while (iscons(c)) {
-            PUSH(car_(c));
-            c = cdr_(c);
-            na++;
-        }
-        if (nargs > 1) {
-            PUSH(args[1]);
-            na++;
-        }
-        size_t cnt = predict_arraylen(&Stack[SP-na], na, &elsz);
+        value_t eltype = car(cdr_(type));
+        int junk;
+        size_t elsz = ctype_sizeof(eltype, &junk);
+        size_t cnt;
+        if (iscons(cdr_(cdr_(type))))
+            cnt = toulong(car_(cdr_(cdr_(type))), "array");
+        else if (nargs == 2)
+            cnt = predict_arraylen(args[1]);
+        else
+            cnt = 0;
         cv = alloc_array(type, elsz * cnt);
-        cvalue_array_init(&Stack[SP-na], na, cv_data((cvalue_t*)ptr(cv)),
-                          (void*)elsz);
-        POPN(na);
+        if (nargs == 2)
+            cvalue_array_init(type, args[1], cv_data((cvalue_t*)ptr(cv)),
+                              (void*)elsz);
     }
     else {
         int junk;
@@ -786,7 +791,8 @@ value_t cvalue_new(value_t *args, u_int32_t nargs)
         if (issymbol(type)) {
             ((cvalue_t*)ptr(cv))->flags.numtype = sym_to_numtype(type);
         }
-        cvalue_init(type, &args[1], nargs-1, cv_data((cvalue_t*)ptr(cv)));
+        if (nargs == 2)
+            cvalue_init(type, args[1], cv_data((cvalue_t*)ptr(cv)));
     }
     return cv;
 }
diff --git a/femtolisp/flisp.c b/femtolisp/flisp.c
index 8f3309e..b37e466 100644
--- a/femtolisp/flisp.c
+++ b/femtolisp/flisp.c
@@ -1433,7 +1433,7 @@ value_t load_file(char *fname)
     FL_TRY {
         while (1) {
             e = read_sexpr(f);
-            //print(ios_stdout,e,0); ios_puts("\n", ios_stdout);
+            //print(ios_stdout,e,0); ios_putc('\n', ios_stdout);
             if (ios_eof(f)) break;
             v = toplevel_eval(e);
         }
@@ -1497,6 +1497,6 @@ int main(int argc, char *argv[])
         set(symbol("that"), v);
         ios_puts("\n\n", ios_stdout);
     }
-    ios_puts("\n", ios_stdout);
+    ios_putc('\n', ios_stdout);
     return 0;
 }
diff --git a/femtolisp/print.c b/femtolisp/print.c
index 9ea009a..54292d7 100644
--- a/femtolisp/print.c
+++ b/femtolisp/print.c
@@ -530,18 +530,22 @@ static void cvalue_printdata(ios_t *f, void *data, size_t len, value_t type,
             if (!weak) {
                 outs("#array(", f);
                 do_print(f, eltype, princ);
-                outc(' ', f);
-            }
-            outc('[', f);
-            for(i=0; i < cnt; i++) {
-                cvalue_printdata(f, data, elsize, eltype, princ, 1);
-                if (i < cnt-1)
+                if (cnt > 0)
                     outc(' ', f);
+            }
+            else {
+                outc('[', f);
+            }
+            for(i=0; i < cnt; i++) {
+                if (i > 0)
+                    outc(' ', f);
+                cvalue_printdata(f, data, elsize, eltype, princ, 1);
                 data += elsize;
             }
-            outc(']', f);
             if (!weak)
                 outc(')', f);
+            else
+                outc(']', f);
         }
         else if (car_(type) == enumsym) {
             value_t sym = list_nth(car(cdr_(type)), *(size_t*)data);
diff --git a/femtolisp/todo b/femtolisp/todo
index 95f9058..f2b1db1 100644
--- a/femtolisp/todo
+++ b/femtolisp/todo
@@ -149,15 +149,14 @@ typedef struct _cvtable_t {
 	void (*print)(struct _cvalue_t *, FILE *);
 } cvtable_t;
 
-; remember: variable-length data preferred over variable-length arglists
-
 c type representations:
 symbols void, [u]int[8,16,32,64], float, double, [u]char, [u]short,
 [u]int, [u]long, lispvalue
 (c-function ret-type (argtype ...))
-(array type N)
+(array type[ N])
 (struct ((name type) (name type) ...))
 (union ((name type) (name type) ...))
+(mlayout ((name type offset) (name type offset) ...))
 (enum (name1 name2 ...))
 (pointer type)
 
@@ -167,8 +166,8 @@ constructors:
 ([u]int64 b3 b2 b1 b0)
 (float hi lo) or (float "3.14")
 (double b3 b2 b1 b0) or (double "3.14")
-(array ctype (val ...))
-(struct ((name type) ...) (val ...))
+(array ctype val ...)
+(struct ((name type) ...) val ...)
 (pointer ctype)      ; null pointer
 (pointer cvalue)     ; constructs pointer to the given value
                      ; same as (pointer (typeof x) x)
@@ -243,11 +242,27 @@ should be related formally:
   (if (symbolp type) (apply (eval type) ())
     (apply (eval (car type)) (cdr type))))
 
+NOTE: this relationship is no longer true. we don't want to have to
+construct 1 cvalue from 1 lisp value every time, since that could
+require allocating a totally redundant list or vector. it should be
+possible to make a cvalue from a series of lisp arguments. for
+example there are now 2 different ways to make an array:
+
+1) from series of arguments: (array type val0 val1 ...)
+2) from 1 (optional) value: (c-value '(array int8[ size])[ V])
+
+constructors will internally use the second form to initialize elements
+of aggregates. e.g. 'array' in the first case will conceptually call
+  (c-value type val0)
+  (c-value type val1)
+  ...
+
+
 for aggregate types, you can keep a variable referring to the relevant
 piece:
 
 (setq point '((x int) (y int)))
-(struct point [2 3])   ; looks like c declaration 'struct point x;'
+(struct point 2 3)   ; looks like c declaration 'struct point x;'
 
 a type is a function, so something similar to typedef is achieved by:
 
@@ -373,10 +388,10 @@ then we can write the vector clause in backquote as e.g.
 
 
 setup plan:
-- create source directory and svn repository, move llt sources into it
+* create source directory and svn repository, move llt sources into it
 * write femtolisp.h, definitions for extensions to #include
 - add fl_ prefix to all exported functions
-- port read and print to jclib's iostreams
+* port read and print to llt iostreams
 * get rid of flutils; use ptrhash instead
 * builtinp needs to be a builtin ;) to distinguish lisp builtins from cvalues
 * allocation and gc for cvalues
@@ -585,6 +600,10 @@ cvalues todo:
 - anonymous unions
 * fix princ for cvalues
 - make header size for primitives 8 bytes, even on 64-bit arch
+- more efficient read for #array(), so it doesn't need to build a pairlist
+- make sure shared pieces of types, like lists of enum values, can be
+  printed as shared structure to avoid duplication.
+- share more types, allocate less
 
 - string constructor/concatenator:
 (string 'sym #char(65) #wchar(945) "blah" 23)
@@ -797,23 +816,30 @@ String API
 
 IOStream API
 
- read
+ read             - (read[ stream]) ; get next sexpr from stream
  print, sprint
  princ, sprinc
- stream           - (stream cvalue-as-bytestream)
+ iostream         - (stream[ cvalue-as-bytestream])
  file
  fifo
  socket
  stream.eof
- stream.write     - (stream.write cvalue)
- stream.read      - (stream.read ctype)
+ stream.write     - (stream.write s cvalue)
+ stream.read      - (stream.read s ctype)
  stream.copy      - (stream.copy to from [nbytes])
  stream.copyuntil - (stream.copy to from byte)
  stream.flush
  stream.pos       - (stream.pos s [set-pos])
  stream.seek      - (stream.seek s offset)
+ stream.seekend   - move to end of stream
  stream.trunc
  stream.getc      - get utf8 character(s)
+ stream.tostring! - destructively convert stringstream to string
+ stream.readline
+ stream.readlines
+ stream.readall
+ print-to-string
+ princ-to-string
 
 
  path.combine
@@ -840,9 +866,11 @@ IOStream API
 
 
 *rand
+*randn
 *rand.uint32
 *rand.uint64
 *rand.double
+*rand.float
 
 -----------------------------------------------------------------------------
 
@@ -880,3 +908,5 @@ switch to miser mode, otherwise default is ok, for example:
 * *print-pretty* to control it
 
 - if indent gets too large, dedent back to left edge
+
+-----------------------------------------------------------------------------
diff --git a/llt/ios.c b/llt/ios.c
index 1127a87..7acd75f 100644
--- a/llt/ios.c
+++ b/llt/ios.c
@@ -189,7 +189,7 @@ static char *_buf_realloc(ios_t *s, size_t sz)
 
 // write a block of data into the buffer at the current position, resizing
 // if necessary. returns # written.
-static size_t _writebuf_force(ios_t *s, char *data, size_t n)
+static size_t _write_grow(ios_t *s, char *data, size_t n)
 {
     size_t amt;
     size_t newsize;
@@ -249,15 +249,14 @@ static size_t _ios_read(ios_t *s, char *dest, size_t n, int all)
             s->bpos += avail;
             return avail;
         }
-        else {
-            dest += avail;
-            n -= avail;
-            tot += avail;
-
-            ios_flush(s);
-            s->bpos = s->size = 0;
-            s->state = bst_rd;
-        }
+        
+        dest += avail;
+        n -= avail;
+        tot += avail;
+        
+        ios_flush(s);
+        s->bpos = s->size = 0;
+        s->state = bst_rd;
         
         if (n > MOST_OF(s->maxsize)) {
             // doesn't fit comfortably in buffer; go direct
@@ -321,6 +320,12 @@ size_t ios_readprep(ios_t *s, size_t n)
     return s->size - s->bpos;
 }
 
+static void _write_update_pos(ios_t *s)
+{
+    if (s->bpos > s->ndirty) s->ndirty = s->bpos;
+    if (s->bpos > s->size)   s->size = s->bpos;
+}
+
 size_t ios_write(ios_t *s, char *data, size_t n)
 {
     if (n == 0) return 0;
@@ -334,7 +339,7 @@ size_t ios_write(ios_t *s, char *data, size_t n)
         space = s->size - s->bpos;
 
     if (s->bm == bm_mem) {
-        wrote = _writebuf_force(s, data, n);
+        wrote = _write_grow(s, data, n);
     }
     else if (s->bm == bm_none) {
         int result = _os_write_all(s->fd, data, n, &wrote);
@@ -366,10 +371,7 @@ size_t ios_write(ios_t *s, char *data, size_t n)
         }
         return ios_write(s, data, n);
     }
-    if (s->bpos > s->ndirty)
-        s->ndirty = s->bpos;
-    if (s->bpos > s->size)
-        s->size = s->bpos;
+    _write_update_pos(s);
     return wrote;
 }
 
@@ -617,7 +619,7 @@ static void _ios_init(ios_t *s)
     s->tally = 0;
     s->fd = -1;
     s->byteswap = 0;
-    s->ownbuf = 0;
+    s->ownbuf = 1;
     s->ownfd = 0;
     s->_eof = 0;
     s->rereadable = 0;
@@ -692,6 +694,13 @@ int ios_putc(int c, ios_t *s)
 {
     char ch = (char)c;
 
+    if (s->state == bst_wr && s->bpos < s->maxsize && s->bm != bm_none) {
+        s->buf[s->bpos++] = ch;
+        _write_update_pos(s);
+        if (s->bm == bm_line && ch == '\n')
+            ios_flush(s);
+        return 1;
+    }
     return (int)ios_write(s, &ch, 1);
 }
 
@@ -754,17 +763,31 @@ int ios_getutf8(ios_t *s, uint32_t *pwc)
 
 int ios_printf(ios_t *s, char *format, ...)
 {
-    char buf[512];
-    char *str=&buf[0];
+    char *str=NULL;
     va_list args;
     int c;
 
     va_start(args, format);
 
-    // TODO: avoid copy
-    c = vsnprintf(buf, sizeof(buf), format, args);
-    if ((size_t)c >= sizeof(buf))
-        c = vasprintf(&str, format, args);
+    if (s->state == bst_wr && s->bpos < s->maxsize && s->bm != bm_none) {
+        size_t avail = s->maxsize - s->bpos;
+        char *start = s->buf + s->bpos;
+        c = vsnprintf(start, avail, format, args);
+        if (c < 0) {
+            va_end(args);
+            return c;
+        }
+        if (c < avail) {
+            va_end(args);
+            s->bpos += (size_t)c;
+            _write_update_pos(s);
+            // TODO: only works right if newline is at end
+            if (s->bm == bm_line && memrchr(start, '\n', (size_t)c))
+                ios_flush(s);
+            return c;
+        }
+    }
+    c = vasprintf(&str, format, args);
 
     va_end(args);
 
@@ -772,6 +795,6 @@ int ios_printf(ios_t *s, char *format, ...)
 
     ios_write(s, str, c);
 
-    if (str != &buf[0]) free(str);
+    free(str);
     return c;
 }