7767 - baremetal/shell: skeleton repl

Prints a fixed value for now, regardless of what is typed.

1 files changed, 127 insertions, 0 deletions

diff --git a/baremetal/121new-stream.subx b/baremetal/121new-stream.subx
new file mode 100644
index 00000000..241f162e
--- /dev/null
+++ b/baremetal/121new-stream.subx
@@ -0,0 +1,127 @@
+# Helper to allocate a stream on the heap.
+
+== 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
+
+new-stream:  # ad: (addr allocation-descriptor), length: int, elemsize: int, out: (addr handle stream _)
+    # . prologue
+    55/push-ebp
+    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
+    # . save registers
+    50/push-eax
+    52/push-edx
+    # var size/edx: int = elemsize*length (clobbering eax)
+    # . eax = elemsize
+    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           0/r32/eax   0x10/disp8      .                 # copy *(ebp+16) to eax
+    # . eax *= length
+    31/xor                          3/mod/direct    2/rm32/edx    .           .             .           2/r32/edx   .               .                 # clear edx
+    f7          4/subop/multiply    1/mod/*+disp8   5/rm32/ebp    .           .                                     0xc/disp8       .                 # multiply *(ebp+12) into edx:eax
+    # . if overflow abort
+    81          7/subop/compare     3/mod/direct    2/rm32/edx    .           .             .           .           .               0/imm32           # compare edx
+    75/jump-if-!=  $new-stream:abort/disp8
+    # . edx = elemsize*length
+    89/copy                         3/mod/direct    2/rm32/edx    .           .             .           0/r32/eax   .               .                 # copy eax to edx
+    # var n/eax: int = size + 12 (for read, write and size)
+    05/add-to-eax  0xc/imm32
+    # allocate(ad, n, out)
+    # . . push args
+    ff          6/subop/push        1/mod/*+disp8   5/rm32/ebp    .           .             .           .           0x14/disp8      .                 # push *(ebp+20)
+    50/push-eax
+    ff          6/subop/push        1/mod/*+disp8   5/rm32/ebp    .           .             .           .           8/disp8         .                 # push *(ebp+8)
+    # . . call
+    e8/call  allocate/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
+    # eax = out->payload
+    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           0/r32/eax   0x14/disp8      .                 # copy *(ebp+20) to eax
+    8b/copy                         1/mod/*+disp8   0/rm32/eax    .           .             .           0/r32/eax   4/disp8         .                 # copy *(eax+4) to eax
+    # skip payload->allocid
+    05/add-to-eax  4/imm32
+    # eax->size = size
+    89/copy                         1/mod/*+disp8   0/rm32/eax    .           .             .           2/r32/edx   8/disp8         .                 # copy edx to *(eax+8)
+    # clear-stream(eax)
+    # . . push args
+    50/push-eax
+    # . . call
+    e8/call  clear-stream/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
+$new-stream:end:
+    # . restore registers
+    5a/pop-to-edx
+    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
+
+$new-stream:abort:
+    (draw-text-wrapping-right-then-down-from-cursor-over-full-screen 0 "new-stream: size too large" 3 0)  # 3=cyan
+    {
+      eb/jump loop/disp8
+    }
+    # never gets here
+
+test-new-stream:
+    # . prologue
+    55/push-ebp
+    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
+    # var ad/ecx: allocation-descriptor containing 16 bytes
+    # . var end/ecx: (addr byte)
+    89/<- %ecx 4/r32/esp
+    # . var start/edx: (addr byte) = end - 32
+    81 5/subop/subtract %esp 0x20/imm32
+    89/<- %edx 4/r32/esp
+    # . ad = {start, end}
+    51/push-ecx
+    52/push-edx
+    89/copy                         3/mod/direct    1/rm32/ecx    .           .             .           4/r32/esp   .               .                 # copy esp to ecx
+    # var start/edx = ad->curr
+    8b/copy                         0/mod/indirect  1/rm32/ecx    .           .             .           2/r32/edx   .               .                 # copy *ecx to edx
+    # var h/ebx: (handle stream byte)
+    68/push  0/imm32
+    68/push  0/imm32
+    89/copy                         3/mod/direct    3/rm32/ebx    .           .             .           4/r32/esp   .               .                 # copy esp to ebx
+    # new-stream(ad, 3, 2, h)
+    # . . push args
+    53/push-ebx
+    68/push  2/imm32
+    68/push  3/imm32
+    51/push-ecx
+    # . . call
+    e8/call  new-stream/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0x10/imm32        # add to esp
+    # eax = out->payload
+    8b/copy                         1/mod/*+disp8   3/rm32/ebx    .           .             .           0/r32/eax   4/disp8         .                 # copy *(ebx+4) to eax
+    # check-ints-equal(eax, edx, msg)
+    # . . push args
+    68/push  "F - test-new-stream: returns current pointer of allocation descriptor"/imm32
+    52/push-edx
+    50/push-eax
+    # . . call
+    e8/call  check-ints-equal/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
+    # skip payload->allocid
+    05/add-to-eax  4/imm32
+    # check-ints-equal(eax->size, 6, msg)
+    # . . push args
+    68/push  "F - test-new-stream: sets size correctly"/imm32
+    68/push  6/imm32
+    ff          6/subop/push        1/mod/*+disp8   0/rm32/eax    .           .             .           .           .               8/disp8           # push *(eax+8)
+    # . . call
+    e8/call  check-ints-equal/disp32
+    # . . discard args
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
+    # the rest is delegated to clear-stream() so we won't bother checking it
+    # . reclaim locals
+    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0x30/imm32        # add to esp
+    # . epilogue
+    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
+    5d/pop-to-ebp
+    c3/return
+
+# . . vim:nowrap:textwidth=0