src/otr

# Read a single byte from a stream.
#
# We need to do this in machine code because streams need to be opaque types,
# and we don't yet support opaque types in Mu.

== code
#   instruction                     effective address                                                   register    displacement    immediate
# . op          subop               mod             rm32          base        index         scale       r32
# . 1-3 bytes   3 bits              2 bits          3 bits        3 bits      3 bits        2 bits      2 bits      0/1/2/4 bytes   0/1/2/4 bytes

# Return next byte value in eax, with top 3 bytes cleared.
# Abort on reaching end of stream.
read-byte:  # s: (addr stream byte) -> result/eax: byte
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # . save registers
    51/push-ecx
    56/push-esi
    # esi = s
    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           6/r32/esi   8/disp8         .                 # copy *(ebp+8) to esi
    # ecx = s->read
    8b/copy                         1/mod/*+disp8   6/rm32/esi    .           .             .           1/r32/ecx   4/disp8         .                 # copy *(esi+4) to ecx
    # if (f->read >= f->write) abort
    3b/compare                      0/mod/indirect  6/rm32/esi    .           .             .           1/r32/ecx   .               .                 # compare ecx with *esi
    0f 8d/jump-if->=  $read-byte:abort/disp32
    # result = f->data[f->read]
    31/xor                          3/mod/direct    0/rm32/eax    .           .             .           0/r32/eax   .               .                 # clear eax
    8a/copy-byte                    1/mod/*+disp8   4/rm32/sib    6/base/esi  1/index/ecx   .           0/r32/AL    0xc/disp8       .                 # copy byte at *(esi+ecx+12) to AL
    # ++f->read
    ff          0/subop/increment   1/mod/*+disp8   6/rm32/esi    .           .             .           .           4/disp8         .                 # increment *(esi+4)
$read-byte:end:
    # . restore registers
    5e/pop-to-esi
    59/pop-to-ecx
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

$read-byte:abort:
    (draw-text-wrapping-right-then-down-from-cursor-over-full-screen 0 "read-byte: empty stream" 3 0)  # 3=cyan
    {
      eb/jump loop/disp8
    }
    # never gets here

== data

_test-input-stream:  # (stream byte)
    # current write index
    0/imm32
    # current read index
    0/imm32
    # size
    0x400/imm32  # 1024 bytes
    # data (64 lines x 16 bytes/line)
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

# . . vim:nowrap:textwidth=0
	Commit message (Expand)	Author	Age	Files	Lines
...
*	Added SMP ui events	James Booth	2014-04-26	1	-6/+6
*	Handle SMP secret response	James Booth	2014-04-26	4	-8/+28
*	Send SMP init message with /otr secret	James Booth	2014-04-26	4	-1/+80
*	Fixed cppcheck warnings	James Booth	2014-04-26	1	-2/+1
*	Merge remote-tracking branch 'lucian/master'	James Booth	2014-04-22	2	-2/+2
\|\
\| *	Modified otrlibv4 and otrlibv4 to add informative message when starting OTR c...	lightb	2014-04-22	2	-2/+2
\| *	Compilation v4 fix	lightb	2014-04-21	2	-4/+0
\| *	Added opportunistic send functionality to cmd_msg	lightb	2014-04-21	2	-0/+4
\| *	Added /otr policy to commands (still need to add autocomplete stuff?)	lightb	2014-04-19	1	-1/+0
\| *	Added PREF_OTR_POLICY to preferences.c -> key -> otr.policy	lightb	2014-04-19	1	-0/+1
\|/
*	Show message in console when contact starts OTR session	James Booth	2014-04-19	1	-1/+1
*	Handle subscription on otr message sends	James Booth	2014-04-18	1	-0/+8
*	OTR end messages are now send to recipients not in the roster.	James Booth	2014-04-18	1	-2/+10
*	Fixed compile error when using libotr 4.0.0	James Booth	2014-04-16	1	-0/+2
*	Tidied ui dependencies	James Booth	2014-04-06	1	-2/+0
*	Renamed refresh functions to update_virtual	James Booth	2014-04-01	1	-1/+1
*	Change libotr 4.0.0 code to use only OTR spec v2	James Booth	2014-03-24	1	-2/+2
*	Updated copyright	James Booth	2014-03-09	5	-5/+5
*	Added OTR supported versions in initial start query message	James Booth	2014-02-18	5	-0/+22
*	Mock otr module for cmd_otr tests	James Booth	2014-02-16	2	-45/+67
*	Only show error message when err != 0	James Booth	2014-02-15	1	-4/+6
*	Removed free message function from otrlibv3	James Booth	2014-02-13	1	-6/+0
*	Refactored common otr library code	James Booth	2014-02-13	4	-813/+547
*	Renamed otr implementations	James Booth	2014-02-12	2	-0/+0
*	Moved otr sources into folder	James Booth	2014-02-12	3	-0/+1054