Move ROM to separate git repository

This commit is contained in:
pjht 2022-11-14 11:02:05 -06:00
parent 09c2db2c33
commit c6e96f3592
7 changed files with 2 additions and 144 deletions

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symbol_tables = ["rom/rom.elf"] symbol_tables = []
[[cards]] [[cards]]
type = "rom" type = "rom"
image = "rom/rom.bin" image = "../rom/rom.bin"
[[cards]] [[cards]]
type = "ram" type = "ram"

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#include <stdint.h>
uint8_t find_all_ram_cards(uint8_t* buf /* a1 */) {
uint8_t len = 0; // move.b 0, d0
void* curr_card = (void*)0xff0000; // a0 = 0xff0000
while(1) { // farc_loop:
curr_card += 0x100; // lea (0x100, a0), a0
uint8_t type = *((uint8_t*)(curr_card+0xff)); // move.b (0xff, a0), d0
if (type == 0) { // beq.b farc_done
break;
}
if (type != 2) { // cmp.b #0x2, d0; bne.b farc_loop
continue;
}
*buf = (uint8_t)((uint32_t)curr_card>>16);
buf += 1; // inc a1
len += 1; // inc d1
} // bra.b farc_loop
// farc_done:
return len;
}
void sort_ram_cards(uint8_t* buf) {
uint8_t len = find_all_ram_cards(buf);
// Insertion sort buf using the aligment of the cards
uint8_t i = 1;
while(1) {
if (i >= len) {
break;
}
uint8_t num = buf[i];
void* card = (void*)((uint32_t)num<<16);
*((uint32_t*)card)=0xfffffffe;
uint32_t x = ~(*((uint32_t*)card)) + 1;
uint8_t j = i - 1;
while(1) {
if (j == 0) {
break;
}
uint8_t num = buf[j];
void* card = (void*)((uint32_t)num<<16);
*((uint32_t*)card)=0xfffffffe;
uint32_t aj = ~(*((uint32_t*)card)) + 1;
if (aj <= x) {
break;
}
buf[j + 1] = buf[j];
j = j - 1;
}
buf[j + 1] = buf[i];
i = i + 1;
}
}

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#! /bin/bash -x
m68k-elf-as -m68010 --register-prefix-optional -o rom.o rom.68k
m68k-elf-ld -z max-page-size=1 -T rom.ld -o rom.elf rom.o
m68k-elf-objcopy -O binary rom.elf rom.bin

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.long fakestack, start
start:
move.b #0x1, d0 | Find the ROM card
bra.b find_first_card
romfindret:
move.l a0, a6 | Save the ROM card IO base in a6 for later
lea (0xF0, a6), a7 | Set up the stack at the end of the ROM's IO space RAM
bsr.b find_largest_ram | Find the largest RAM card and put the IO base in a5
move.l a0, a5
move.l d0, d7
move.b #0x4, d0 | Find a storage card and put the IO base in a4
bsr.b find_first_card
move.l a0, a4
| Transfer the bootsector load code to the ROM's
| built in RAM at the start of it's IO space
move.w #(ramcode_end - ramcode), d0 | Put the length of the ramcode in d0
move.w #ramcode, a0 | Put the address of the ramcode in a0
move.l a6, a1 | Put the start of the ROM's IO space RAM in a0
ramcode_loop:
move.b (a0)+, (a1)+ | Transfer a byte of ramcode to the ROM's IO space RAM
dbra d0, ramcode_loop | Loop back if there is more to transfer
jmp (a6) | Jump to the ramcode
stop #0x2700
ramcode:
move.b #0x0, (0xFE, a6) | Disable the ROM
move.l #0x1, (a5) | Enable the RAM at base 0x0
move.l d7, a7
| Load sector 0 to 0x0
move.l #0x0, (a4) | Set the sector number to 0
| Transfer 0x100 (256) bytes from the storage card's data register to 0x0
move.w #0x0, a1 | Load a1, the destination address register, with 0x0
move.w #0xFF, d0 | Load d0 with the sector size - 1.
sector_loop:
move.b (4, a4), (a1)+ | Transfer a byte of sector data to the destination
dbra d0, sector_loop | Loop back if there is more to transfer
jmp (0x0).W | Jump to the loaded sector
stop #0x2700
ramcode_end:
nop | Padding to make sure ramcode_end and find_first_card are different
| Finds the first card with the type in d0.b, and returns it's IO base address in a0, or 0 if not found
| Clobbers d1
find_first_card:
move.l #0xff0000, a0 | a0 holds the address of the current card
ffc_loop:
lea (0x100,a0), a0 | adda.l #$100,a0 ; Move to the next card
move.b (0xff, a0), d1 | Load the type of the card into d1
beq.b ffc_done | If the type is 0 (empty slot), we have scanned all cards, so exit the loop
cmp.b d0, d1 | If the card is the type we want, return with the address in a0
beq.b ffc_done
bra.b ffc_loop | Loop back and check the next card
ffc_done:
rts
| Finds the largest RAM card, and returns it's IO base address in a0 and size in d0, or 0 if not found
| Clobbers d1, a1
find_largest_ram:
move.l #0x0, d0 | d0 holds the size of the largest RAM card found
move.w #0x0, a0 | a0 holds the address of the largest RAM card found
move.l #0xff0000, a1 | a1 holds the address of the current card
flr_loop:
lea (0x100,a1), a1 | adda.l #$100,a0 ; Move to the next card
move.b (0xff, a1), d1 | Load the type of the card into d1
beq.b flr_done | If the type is 0 (empty slot), we have scanned all cards, so exit the loop
cmp.b #0x2, d1 | If the card isn't a RAM card, skip it
bne.b flr_loop
move.l (0x4, a1), d1 | Load the card's size into d1
cmp.l d0, d1 | If the current size is less than the largest size found, go back to the start of the loop
ble.b flr_loop
move.l d1, d0 | Store the size and address of the new largest card in d0 and a0
move.l a1, a0
bra.b flr_loop | Loop back and check the next card
flr_done:
rts
fakestack:
.long romfindret

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SECTIONS {
. = 0x0;
_etext = .;
.text : { *(.text) }
}