Initial working commit

.gitignore

@@ -0,0 +1,7 @@
+/*
+/*/
+!/.gitignore
+
+!/charset.S
+!/first.S
+!/Makefile

Makefile

@@ -0,0 +1,40 @@
+PATH := $(DEVKITARM)/bin:$(DEVKITPRO)/tools/bin:$(PATH)
+
+PROJ    := first
+TARGET  := $(PROJ)
+
+PREFIX  := arm-none-eabi-
+CC      := $(PREFIX)gcc
+OBJCOPY := $(PREFIX)objcopy
+OBJDUMP := $(PREFIX)objdump
+FIX		:= gbafix
+
+ARCH    := -mthumb-interwork -mthumb
+SPECS   := -specs=gba.specs
+
+SOURCES := first.S charset.S
+
+.PHONY : build clean
+
+build: $(TARGET).gba
+
+debug: $(TARGET).elf $(TARGET).debug.elf
+
+first.dump: first.elf
+	$(OBJDUMP) -d $<
+
+first.gba: first.unfixed.gba
+	gbafix -p -d1 $<
+
+first.unfixed.gba: first.elf
+	$(OBJCOPY) -v -O binary $< $@
+
+first.debug.elf: $(SOURCES)
+	$(CC) $(ARCH) $(SPECS) -g -o $@ $^
+
+first.elf: $(SOURCES)
+	$(CC) $(ARCH) $(SPECS) -o $@ $^
+
+clean:
+	rm *.gba
+	rm *.elf

first.S

@@ -0,0 +1,88 @@
+    .arm
+                                //.align 2
+
+    .text
+                                //.section .text, "ax", %progbits
+    .global main
+main:
+    mov     r0, #0x04000000
+    mov     r1, #0x0003
+    orr     r1, #0x0400
+    str     r1, [r0]
+
+letters:
+    ldr     r0, .VID_MEM        // r0 := &(video memory)
+    mov     r1, #0x001F         // r1 == Color::red => color to draw pixels in
+
+    mov     r4, #0              // r4 => table offset for the letter
+
+    mov     r5, #8              // r5 == 8  => letter column counter
+    mov     r6, #8              // r6 == 8  => letter row    counter
+
+    mov     r7, #0x1C           // r7 == 30 => screen column counter
+    mov     r8, #0x7F           // r8 == 28 => letter number counter
+                                //       /\
+                                //       ||
+                                //       (0x7f for all letters, which won't fit the screen or the VID_MEM)
+
+    ldr     r2, =.NESfont       // r2 => &(font table)
+
+    ldrb    r3, [r2, r4]        // r3 := first row of pixels
+
+1:
+    tst     r3, #0b10000000     // \     \     \     \ if (leftmost bit of bitfield is set)
+    beq     2f
+
+    strh    r1, [r0]            // |     |     |     |     draw pixel with color
+                                // |     |     |     /
+
+2:
+    lsl     r3, r3, #1          // |     |     |     r3 := next letter column
+    add     r0, #2              // |     |     |     r0 := next pixel
+
+    subs    r5, #1              // |     |     |
+    bne     1b                  // |     |     / while (r5 > 0 => columns to process)
+
+    add     r4, r4, #1          // |     |     \ next letter row
+    ldrb    r3, [r2, r4]        // |     |     /
+
+    subs    r6, #1              // |     |
+    beq     3f                  // |     |     break
+
+    add     r0, r0, #464        // |     |     r0 += row - letter width (8x2) => next screen row, first box column
+    mov     r5, #8              // |     |     reset column counter
+
+    b       1b                  // |     / while (r6 > 0)
+
+3:
+    mov     r5, #8              // |     reset column counter
+    mov     r6, #8              // |     reset row counter
+
+    subs    r8, #1              // |     => one letter done
+    beq     infin               // |     > return if (last letter)
+
+    subs    r7, #1              // |     => one screen column used
+    beq     4f                  // |     => screen row full
+
+    ldr     r9, =0x0D1F         // |     r9 == 0x0D1E + (1 apparently?!)
+    sub     r0, r0, r9          // |     r0 := next box
+
+    b       1b
+
+4:
+    mov     r7, #0x1C           // |     reset screen column counter
+    add     r0, #5              // |     r0 := 2 => next pixel (wraps around to next row) + pixel left empty at the right of the screen
+
+    b       1b                  // / while (r8 > 0)
+
+
+
+infin:
+    b       infin
+
+    .VID_MEM:
+    .long   0x06000000          // &(video memory)
+
+                                // Local Variables:
+                                // mode: asm
+                                // End: