duskos

commit af1a0fb2efb6c243235162b9b442487838152d78
parent aa6031fab22b775bab05537f9126292c4260ab84
Author: Virgil Dupras <hsoft@hardcoded.net>
Date:   Wed,  1 Jun 2022 13:51:40 -0400

Add emit

This is getting exciting!

Diffstat:
M
Makefile
 | 
7
+++----
M
dusk.asm
 | 
3
+++
M
word_macros.asm
 | 
10
++++++++++
M
words/boot.asm
 | 
14
+++-----------
A
words/emit.asm
 | 
8
++++++++

5 files changed, 27 insertions(+), 15 deletions(-)
diff --git a/Makefile b/Makefile
@@ -1,15 +1,14 @@
 TARGETS = dusk
+WORDOBJS = $(addsuffix .o,$(addprefix words/,bye emit boot))
 
 all: $(TARGETS)
 
 %.o: %.asm
 	nasm -f elf32 -p word_macros.asm $< -o $@
 
-words/boot.o: words/boot.asm
-words/bye.o: words/bye.asm
-dusk: dusk.asm words/boot.o words/bye.o
+dusk: dusk.asm $(WORDOBJS)
 	nasm -f elf32 dusk.asm -o dusk.o
-	ld -m elf_i386 dusk.o words/*.o -o $@
+	ld -m elf_i386 dusk.o $(WORDOBJS) -o $@
 	
 .PHONY: clean
 clean:
diff --git a/dusk.asm b/dusk.asm
@@ -1,3 +1,4 @@
+; PSP=ebp RSP=esp
 BITS 32
 %define PS_SZ 4096
 %define RS_SZ 4096
@@ -13,5 +14,7 @@ SECTION .text
 
 _start:
 	cld
+    mov esp, rs_top
+    mov ebp, ps_top
     call word_boot
     call word_bye
diff --git a/word_macros.asm b/word_macros.asm
@@ -1,3 +1,13 @@
+%macro pspush 1 ; src
+    sub ebp, 4 
+    mov dword [ebp], %1
+%endmacro
+
+%macro pspop 1 ; dst
+    mov %1, dword [ebp]
+    add ebp, 4
+%endmacro
+
 %macro _word 4 ; name namelen lbl prevlbl
 GLOBAL %3
 db %1
diff --git a/words/boot.asm b/words/boot.asm
@@ -1,12 +1,4 @@
-SECTION .data
-hello:     db 'Hello world!',10
-len:  equ $-hello
-
-SECTION .text
-defword 'boot', 4, word_boot, word_bye
-    mov eax,4            ; 'write' syscall
-    mov ebx,1            ; stdout
-    mov ecx,hello       
-    mov edx,len   
-    int 80h           
+defword 'boot', 4, word_boot, word_emit
+    pspush 0x66 ; 'f'
+    call word_emit
     ret
diff --git a/words/emit.asm b/words/emit.asm
@@ -0,0 +1,8 @@
+defword 'emit', 4, word_emit, word_bye
+    mov eax,4            ; 'write' syscall
+    mov ebx,1            ; stdout
+    mov ecx,ebp          ; top of PS, little endian
+    mov edx,1   
+    int 80h
+    pspop eax
+    ret