Can jump to and execute Debug ROM.

Connect with gdb, and the core will jump to Debug ROM and start
executing it. Then it crashes when it jumps to 0x400 because Debug RAM
isn't implemented (and doesn't live there anyway, for now).

1 files changed, 0 insertions, 105 deletions

diff --git a/debug_rom/debug_rom.S b/debug_rom/debug_rom.S
deleted file mode 100755
index 230f4b4..0000000
--- a/debug_rom/debug_rom.S
+++ /dev/null
@@ -1,105 +0,0 @@
-# This code should be functional. Doesn't have to be optimal.
-# I'm writing it to prove that it can be done.
-
-# TODO: Update these constants once they're finalized in the doc.
-
-#define DCSR                    0x790
-#define DCSR_CAUSE_DEBINT       3
-#define DCSR_HALT_OFFSET        3
-#define DCSR_DEBUGINT_OFFSET    10
-
-#define DSCRATCH                0x792
-
-#define MCPUID                  0xf00
-#define MHARTID                 0xf10
-
-#define DEBUG_RAM               0x400
-#define DEBUG_RAM_SIZE          64
-
-#define SETHALTNOT              0x100
-#define CLEARHALTNOT            0x104
-#define CLEARDEBINT             0x108
-
-        .global entry
-        .global resume
-
-        # Automatically called when Debug Mode is first entered.
-entry:  j       _entry
-        # Should be called by Debug RAM code that has finished execution and
-        # wants to return to Debug Mode.
-resume:
-        # Clear debug interrupt.
-clear_debint:
-        csrr    s1, MHARTID
-        sw      s1, CLEARDEBINT(zero)
-clear_debint_loop:
-        csrr    s1, DCSR
-        andi    s1, s1, (1<<DCSR_DEBUGINT_OFFSET)
-        bnez    s1, wait_for_interrupt
-
-        # Restore s1.
-        csrr    s1, MCPUID
-        bltz    s1, restore_not_32
-restore_32:
-        lw      s1, (DEBUG_RAM + DEBUG_RAM_SIZE - 4)(zero)
-        j       check_halt
-restore_not_32:
-        slli    s1, s1, 1
-        bltz    s1, restore_128
-restore_64:
-        ld      s1, (DEBUG_RAM + DEBUG_RAM_SIZE - 8)(zero)
-        j       check_halt
-restore_128:
-        nop     #lq      s1, (DEBUG_RAM + DEBUG_RAM_SIZE - 16)(zero)
-
-check_halt:
-        csrr    s0, DCSR
-        andi    s0, s0, (1<<DCSR_HALT_OFFSET)
-        beqz    s0, exit
-        j       wait_for_interrupt
-
-exit:
-        # Restore s0.
-        csrr    s0, DSCRATCH
-        eret
-
-
-_entry:
-        # Save s0 in DSCRATCH
-        csrw    DSCRATCH, s0
-
-        # Check why we're here
-        csrr    s0, DCSR
-        # cause is in bits 2:0 of dcsr
-        andi    s0, s0, 7
-        addi    s0, s0, -DCSR_CAUSE_DEBINT
-        bnez    s0, spontaneous_halt
-
-jdebugram:
-        # Save s1 so that the debug program can use two registers.
-        csrr    s0, MCPUID
-        bltz    s0, save_not_32
-save_32:
-        sw      s1, (DEBUG_RAM + DEBUG_RAM_SIZE - 4)(zero)
-        jr      zero, DEBUG_RAM
-save_not_32:
-        slli    s0, s0, 1
-        bltz    s0, save_128
-save_64:
-        sd      s1, (DEBUG_RAM + DEBUG_RAM_SIZE - 8)(zero)
-        jr      zero, DEBUG_RAM
-save_128:
-        nop     #sq      s1, (DEBUG_RAM + DEBUG_RAM_SIZE - 16)(zero)
-        jr      zero, DEBUG_RAM
-
-spontaneous_halt:
-        csrr    s0, MHARTID
-        sw      s0, SETHALTNOT(zero)
-        csrsi   DCSR, DCSR_HALT_OFFSET
-
-wait_for_interrupt:
-        csrr    s0, DCSR
-        andi    s0, s0, (1<<DCSR_DEBUGINT_OFFSET)
-        beqz    s0, wait_for_interrupt
-
-        j       jdebugram