Rename boot to bios, add sd call

Adds a call that you can make to the BIOS to read sd blocks. Useful for
the bootloader where there is not much space

sw/bios/Makefile

@@ -2,12 +2,8 @@ CC=cl65
 CFLAGS=-T -t none -I. --cpu "65C02"
 test: CFLAGS=-T -t sim65c02 -I.
 LDFLAGS=-C link.ld -m $(NAME).map
-SIM=sim65
+NAME=bios
-SIMARGS=-v -c -x 1000000
 
-NAME=bootrom
-
-TEST_BIN=test.bin
 BIN=$(NAME).bin
 HEX=$(NAME).hex
 

sw/bios/boot.s

@@ -1,11 +1,8 @@
-; We need to to read the boot sector from the
-; SD card, verify the last 2 bytes, then jump to the
-; beginning of it.
-
 .include "zeropage.inc"
 
 .segment "STARTUP"
 
+.export _init
 .import _load_bootsect
 
 _init:  ldx #$ff

sw/bios/devices/interrupt.s

@@ -0,0 +1,55 @@
+.include "io.inc65"
+
+.export   _irq_int, _nmi_int
+
+.importzp sreg, ptr1
+
+.segment  "CODE"
+
+; IRQ
+_irq_int:
+        jmp (irqmap,x)
+
+_nmi_int:
+        rti
+
+irqmap:
+        .addr handle_invalid
+        .addr handle_sd_read
+
+handle_invalid:
+        rti
+
+; sreg is the pointer to store the data
+; a/y is the block address
+; send command 17 with the block address of 00/y/a
+handle_sd_read:
+        sta SD_ARG          ; send command
+        sty SD_ARG+1
+        stz SD_ARG+2
+        stz SD_ARG+3
+        lda #$11
+        sta SD_CMD
+
+@1:     lda SD_CMD          ; wait for status flag
+        and #$01
+        beq @1
+
+@2:     lda SD_CMD          ; wait for data
+        and #$02
+        beq @2
+
+        ldy #$00
+@loop:  lda SD_DATA         ; copy first 256 bytes
+        sta (sreg),y
+        iny
+        bne @loop
+
+        ldy #$00            ; copy second 256 bytes
+        inc sreg+1
+@loop2: lda SD_DATA
+        sta (sreg),y
+        iny
+        bne @loop2
+
+        rti

sw/bios/link.ld

@@ -14,5 +14,6 @@ SEGMENTS {
     ONCE:     load = ROM, type = ro,  optional = yes;
     CODE:     load = ROM, type = ro;
     RODATA:   load = ROM, type = ro;
+    VECTORS:  load = ROM, type = ro,  start    = $FFFA;
 }
 

sw/bios/vectors.s

@@ -0,0 +1,14 @@
+; ---------------------------------------------------------------------------
+; vectors.s
+; ---------------------------------------------------------------------------
+;
+; Defines the interrupt vector table.
+
+.import    _init
+.import    _nmi_int, _irq_int
+
+.segment  "VECTORS"
+
+.addr      _nmi_int    ; NMI vector
+.addr      _init       ; Reset vector
+.addr      _irq_int    ; IRQ/BRK vector