add an exploration towards moving code generation to its own file

this is re-tracing some steps from way back in the beginning, to see what they look like in a post-flatassembler context :)

it doesn't, like, do anything yet, other than print out some introspection

Force-Push: yes
Change-Id: I8913edffc075de313870367ef56278b1c8f50a06

1 files changed, 98 insertions, 0 deletions

diff --git a/make-hello.e b/make-hello.e
new file mode 100644
index 0000000..55f62d6
--- /dev/null
+++ b/make-hello.e
@@ -0,0 +1,98 @@
+~ current output point, string pointer
+: pack-raw-string
+  { unpack8 dup } { 3roll swap pack8 swap } while drop drop ;
+
+: origin 0x08000000 ;
+
+heap hexdump latest @ .hex space here @ .hex newline
+latest @ @ word-heading latest @ @ hexdump
+latest @ word-heading latest @ hexdump
+: foo
+  latest @ word-heading latest @ hexdump
+  ~ s" labels" create
+  8 allocate s" labels" variable
+  ;
+foo
+latest @ word-heading latest @ hexdump
+
+s" labels" find .hex bye
+
+~ ~~
+~ ~~ ELF header
+~ ~~
+~ ~~   This is the top-level ELF header, for the entire file. An ELF always
+~ ~~ has exactly one of this header, which is always at the start of the file.
+~ ~~
+: elf-file-header
+  0x7f pack8 s" ELF" pack-raw-string        ~ magic number
+  2 pack8                                   ~ 64-bit
+  1 pack8                                   ~ little-endian
+  1 pack8                                   ~ ELF header format v1
+  0 pack8                                   ~ System-V ABI
+  0 pack64                                  ~ (padding)
+
+  2 pack16                                  ~ executable
+  0x3e pack16                               ~ Intel x86-64
+  1 pack32                                  ~ ELF format version
+
+  ~ Compute the entry pointer.
+  origin 0x78 + pack64                      ~ entry point
+    ~ This includes the origin, intentionally.
+
+  0 pack64                                  ~ program header offset
+    ~ We place the program header immediately after the ELF header. This
+    ~ offset is from the start of the file.
+  0 pack64                                  ~ section header offset
+  0 pack32                                  ~ processor flags
+  64 pack16                                 ~ ELF header size
+  56 pack16                                 ~ program header entry size
+  1 pack16                                  ~ number of program header entries
+  0 pack16                                  ~ section header entry size
+  0 pack16                                  ~ number of section header entries
+  0 pack16                                  ~ section name string table index
+  ;
+
+~ ~~
+~ ~~ Program header
+~ ~~
+~ ~~   An ELF program header consists of any number of these entries; they are
+~ ~~ always consecutive, but may be anywhere in the file. We always have
+~ ~~ exactly one, and it's always right after the ELF file header.
+~ ~~
+: elf-program-header
+  1 pack32                                  ~ "loadable" segment type
+  0x05 pack32                               ~ read+execute permission
+  0 pack64                                  ~ offset in file
+  origin pack64                             ~ virtual address
+    ~ required, but can be anything, subject to alignment
+  0 pack64                                  ~ physical address (ignored)
+
+  ~ Fill in 0 as the file size for now, to avoid uninitialized memory.
+  0 pack64                                  ~ size in file
+    ~ TODO call use-label here
+  0 pack64                                  ~ size in memory
+    ~ TODO call use-label here
+
+  0 pack64                                  ~ segment alignment
+    ~ for relocation, but this doesn't apply to us
+  ;
+
+: output-start-routine
+  ~ lit 1 :rax mov-reg64-imm32
+  ;
+
+: all-contents
+  ~ current output point
+  elf-file-header
+  elf-program-header
+  output-start-routine
+  ;
+
+0x1000 allocate dup
+~ output memory start, current output point
+
+all-contents
+
+~ output memory start, current output point
+over - swap sys-write bye
+