diff options
Diffstat (limited to 'apps/ex8.subx')
| -rw-r--r-- | apps/ex8.subx | 60 |
1 files changed, 0 insertions, 60 deletions
diff --git a/apps/ex8.subx b/apps/ex8.subx deleted file mode 100644 index 84d27195..00000000 --- a/apps/ex8.subx +++ /dev/null @@ -1,60 +0,0 @@ -# Example reading commandline arguments: compute length of first arg. -# -# To run: -# $ ./bootstrap translate init.linux apps/ex8.subx -o apps/ex8 -# $ ./bootstrap run apps/ex8 abc de fghi -# Expected result: -# $ echo $? -# 3 # length of 'abc' -# -# At the start of a SubX program: -# argc: *esp -# argv[0]: *(esp+4) -# argv[1]: *(esp+8) -# ... -# Locals start from esp-4 downwards. - -== code -# instruction effective address register displacement immediate -# . op subop mod rm32 base index scale r32 -# . 1-3 bytes 3 bits 2 bits 3 bits 3 bits 3 bits 2 bits 2 bits 0/1/2/4 bytes 0/1/2/4 bytes - -Entry: - # . prologue - 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp - # eax = ascii-length(argv[1]) - # . . push args - ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 8/disp8 . # push *(ebp+8) - # . . call - e8/call ascii-length/disp32 - # . . discard args - 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp - - # exit(eax) - 89/copy 3/mod/direct 3/rm32/ebx . . . 0/r32/eax . . # copy eax to ebx - e8/call syscall_exit/disp32 - -ascii-length: # s: (addr array byte) -> n/eax - # edx = s - 8b/copy 1/mod/*+disp8 4/rm32/sib 4/base/esp 4/index/none . 2/r32/edx 4/disp8 . # copy *(esp+4) to edx - # var result/eax = 0 - b8/copy-to-eax 0/imm32 -$ascii-length:loop: - # var c/ecx = *s - 8a/copy-byte 0/mod/* 2/rm32/edx . . . 1/r32/CL . . # copy byte at *edx to CL - # if (c == '\0') break - 81 7/subop/compare 3/mod/direct 1/rm32/ecx . . . . . 0/imm32/null # compare ecx - 74/jump-if-= $ascii-length:end/disp8 - # ++s - 42/increment-edx - # ++result - 40/increment-eax - # loop - eb/jump $ascii-length:loop/disp8 -$ascii-length:end: - # return eax - c3/return - -== data - -# . . vim:nowrap:textwidth=0 |