Initial commit.

3 files changed, 291 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..5761abc
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+*.o
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..cdd89df
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,17 @@
+NASMFLAGS = -f elf
+
+all: libmalice.o
+
+libmalice.o: libmalice.asm
+	nasm $(NASMFLAGS) -o $@ $<
+
+.PHONY : clean
+clean:
+	rm -f *.o
+
+.PHONY : distclean
+distclean: clean
+	rm -f *~
+
+.PHONY : test
+test: all
diff --git a/libmalice.asm b/libmalice.asm
new file mode 100644
index 0000000..adb9907
--- /dev/null
+++ b/libmalice.asm
@@ -0,0 +1,273 @@
+; libmalice
+
+; Code for Linux on IA-32.
+
+extern lmMain
+
+section .text ; start of code
+global _lmStart ; export the entry point function
+
+
+
+_lmStart:
+mov [__start_esp], esp
+call lmMain
+_start_end:
+mov esp, [__start_esp]
+	; Cleanup can be done here if necessary
+mov ebx, eax
+mov eax, 1
+int 0x80
+
+
+
+
+
+; lmExit - Terminate safely from any position in the program
+
+global lmExit
+lmExit:	; void lmExit(int exitstatus)
+mov eax, [esp+4]	; pass the exit status through as eax
+jmp _start_end	; poor man's exception handling
+	; ret is not necessary
+
+
+
+
+
+; lmPrintChar - Print one character to stdout (8-bit in 32-bit, LSB)
+
+global lmPrintChar
+lmPrintChar:	; void lmPrintChar(int chr)
+push eax	; will be: syscall number
+push ebx 	; will be: stdout fd
+push ecx 	; will be: character start address
+push edx	; will be: character counter
+
+mov  edx, 1	; print one char
+lea  ecx, [esp+20]	; address of the char
+mov  ebx, 1	; stdout fd
+mov  eax, 4	; write()
+int 0x80
+
+pop edx
+pop ecx
+pop ebx
+pop eax
+ret
+
+
+
+
+
+; lmPrintString - Print a null-terminated string to stdout
+
+global lmPrintString
+lmPrintString:	; void lmPrintString(char *string)
+push eax	; will be: syscall number
+push ebx 	; will be: stdout fd
+push ecx 	; will be: character start address
+push edx	; will be: character counter
+
+mov  eax, 0		; prepare for holding a char
+mov  ecx, [esp+20]	; string start address
+mov  edx, -1		; init char counter to 0
+
+_print_string_loop:
+	inc  edx		; char_counter++
+	mov  al, [ecx+edx]	; check next char
+cmp al, 0			; if != '\0' continue
+jne _print_string_loop
+
+mov  ebx, 1	; stdout fd
+mov  eax, 4	; write()
+int 0x80
+
+pop edx
+pop ecx
+pop ebx
+pop eax
+ret
+
+
+
+
+
+; lmPrintInt32s - Print an integer to stdout (signed, 32-bit)
+
+global lmPrintInt32s
+lmPrintInt32s:	; void lmPrintInt(int num)
+push eax	; will be: dividend
+push ebx	; will be: divisor
+push ecx 	; will be: character start address
+push edx	; will be: character counter
+mov eax, [esp+20]	; load num
+sub esp, 12		; make space for converted integer
+lea ecx, [esp+11]	; string offset counter, start at lastchar+1
+			; so writing ends at 10 and char 11 is reserved
+
+mov ebx, 10		; always divide by 10
+
+cmp eax, dword 0	; if the number is negative, negate
+jge _print_int_loop
+neg eax			; great fun at -2147483648. Overflow ftw!
+
+_print_int_loop:
+	mov edx, 0
+	idiv ebx
+	add edx, 0x30
+	dec ecx		; write next char
+	mov [ecx], dl
+test eax, eax
+jne _print_int_loop
+
+cmp [esp+32], dword 0	; check for negative number
+jge _print_int_end	; skip for positive
+dec ecx
+mov [ecx], byte '-'	; add - sign
+
+_print_int_end:
+lea edx, [esp+11]
+sub edx, ecx	; number of chars
+mov  ebx, 1	; stdout fd
+mov  eax, 4	; write()
+int 0x80	; let the number speak
+
+add esp, 12
+pop edx
+pop ecx
+pop ebx
+pop eax
+ret
+
+
+
+
+
+; lmReadChar - Read a character from stdin (8-bit in 32-bit, LSB)
+
+global lmReadChar
+lmReadChar:	; int lmReadChar(void)
+push ebx
+push ecx
+push edx
+
+sub esp, 4	; make room for character to be read
+
+mov edx, 1	; number of chars
+mov ecx, esp	; character buffer
+mov ebx, 0	; stdin fd
+mov eax, 3	; read()
+int 0x80
+
+cmp eax, 0
+jne _read_char_ok	; No end of input -> return char
+
+mov eax, 0		; End of Input -> return 0
+jmp _read_char_end
+
+_read_char_ok:
+mov eax, 0
+mov al, [esp]
+
+_read_char_end:
+add esp, 4
+pop edx
+pop ecx
+pop ebx
+ret
+
+
+
+
+
+; lmReadInt32s - Read an integer from stdin (signed, 32-bit)
+;                       Terminated by EOF or LF
+
+global lmReadInt32s
+lmReadInt32s:	; int lmReadInt(void)
+push ebx
+push ecx
+push edx
+push esi	; negative number info
+push edi	; actual number
+
+sub esp, 4	; make room for character to be read
+
+mov esi, 0	; 0 = positive
+mov edi, 0	; start with 0
+
+
+_read_int_next:
+mov edx, 1	; number of chars
+mov ecx, esp	; character buffer
+mov ebx, 0	; stdin fd
+mov eax, 3	; read()
+int 0x80
+
+cmp eax, 0
+je _read_int_neg	; End of input
+
+mov eax, 0
+mov al, [esp]
+
+cmp al, '-'
+jne _read_int_process_digit
+mov esi, 1
+jmp _read_int_next
+
+_read_int_process_digit:
+cmp al, 0x30
+jb _read_int_neg	; char < '0'
+cmp al, 0x39
+ja _read_int_neg	; char > '9'
+
+sub eax, 0x30
+imul edi, 10	; shift old digits
+add edi, eax	; add new digit
+
+jmp _read_int_next
+
+
+_read_int_neg:
+test esi, esi
+jz _read_int_skip_loop
+neg edi
+
+
+_read_int_skip_loop:	; read and skip until newline is encountered
+cmp byte [esp], 0x0a
+je _read_int_end	; if newline found -> end reading
+
+mov edx, 1	; number of chars
+mov ecx, esp	; character buffer
+mov ebx, 0	; stdin fd
+mov eax, 3	; read()
+int 0x80
+
+cmp eax, 0
+je _read_int_end	; End of input -> end reading
+
+jmp _read_int_skip_loop
+
+
+_read_int_end:
+mov eax, edi	; Return value: The number read
+
+add esp, 4
+pop edi
+pop esi
+pop edx
+pop ecx
+pop ebx
+ret
+
+
+
+
+
+
+
+section .data
+
+__start_esp: dd 0