From c95648c96093ce0d44c21191bab0ee2c9b04becc Mon Sep 17 00:00:00 2001
From: "Kartik K. Agaram" <vc@akkartik.com>
Date: Sat, 3 Jul 2021 18:27:01 -0700
Subject: reading from streams

The Mu shell has no string literals, only streams. No random access,
only sequential access. But I've been playing fast and loose with its
read pointer until now. Hopefully things are cleaned up now.
---
 113write-stream.subx | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

(limited to '113write-stream.subx')

diff --git a/113write-stream.subx b/113write-stream.subx
index 7dd93fba..4478179b 100644
--- a/113write-stream.subx
+++ b/113write-stream.subx
@@ -158,6 +158,53 @@ test-write-stream-appends:
     # . end
     c3/return
 
+# like write-stream, but don't update s->read
+# is there a better name for this?
+write-stream-immutable:  # f: (addr stream byte), s: (addr stream byte)
+    # . prologue
+    55/push-ebp
+    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
+    # . save registers
+    50/push-eax
+    56/push-esi
+    57/push-edi
+    # edi = f
+    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .                         7/r32/edi   8/disp8         .                 # copy *(ebp+8) to edi
+    # esi = s
+    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .                         6/r32/esi   0xc/disp8       .                 # copy *(ebp+12) to esi
+    # eax = _append-4(&f->data[f->write], &f->data[f->size], &s->data[s->read], &s->data[s->write])
+    # . . push &s->data[s->write]
+    8b/copy                         0/mod/indirect  6/rm32/esi    .           .             .           0/r32/eax   .               .                 # copy *esi to eax
+    8d/copy-address                 1/mod/*+disp8   4/rm32/sib    6/base/esi  0/index/eax   .           0/r32/eax   0xc/disp8       .                 # copy esi+eax+12 to eax
+    50/push-eax
+    # . . push &s->data[s->read]
+    8b/copy                         1/mod/*+disp8   6/rm32/esi    .           .             .           0/r32/eax   4/disp8         .                 # copy *(esi+4) to eax
+    8d/copy-address                 1/mod/*+disp8   4/rm32/sib    6/base/esi  0/index/eax   .           0/r32/eax   0xc/disp8       .                 # copy esi+eax+12 to eax
+    50/push-eax
+    # . . push &f->data[f->size]
+    8b/copy                         1/mod/*+disp8   7/rm32/edi    .           .             .           0/r32/eax   8/disp8         .                 # copy *(edi+8) to eax
+    8d/copy-address                 1/mod/*+disp8   4/rm32/sib    7/base/edi  0/index/eax   .           0/r32/eax   0xc/disp8       .                 # copy edi+eax+12 to eax
+    50/push-eax
+    # . . push &f->data[f->write]
+    8b/copy                         0/mod/indirect  7/rm32/edi    .           .             .           0/r32/eax   .               .                 # copy *edi to eax
+    8d/copy-address                 1/mod/*+disp8   4/rm32/sib    7/base/edi  0/index/eax   .           0/r32/eax   0xc/disp8       .                 # copy edi+eax+12 to eax
+    50/push-eax
+    # . . call
+    e8/call  _append-4/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0x10/imm32        # add to esp
+    # f->write += eax
+    01/add                          0/mod/indirect  7/rm32/edi    .           .             .           0/r32/eax   .               .                 # add eax to *edi
+$write-stream-immutable:end:
+    # . restore registers
+    5f/pop-to-edi
+    5e/pop-to-esi
+    58/pop-to-eax
+    # . epilogue
+    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
+    5d/pop-to-ebp
+    c3/return
+
 == data
 
 _test-stream2:  # (stream byte)
-- 
cgit 1.4.1-2-gfad0