diff options
| -rw-r--r-- | README.md | 22 | ||||
| -rw-r--r-- | hexedit/Makefile | 21 | ||||
| -rw-r--r-- | hexedit/hexedit.s | 122 | ||||
| -rw-r--r-- | hexedit/main.s | 13 | ||||
| -rw-r--r-- | hexedit/pico_ram_only.ld | 14 |
5 files changed, 184 insertions, 8 deletions
@@ -2,24 +2,30 @@ I'm starting over. -## Hexedit +## Octedit -This is a bare-minimum hex editor -which fits entirely within the 252-byte boot sector +This is a bare-minimum memory editor +which fits entirely within the 256-byte boot sector of the Raspberry Pi Pico's on-board flash. - Most of the space is dedicated to setting up the clocks, GPIO, and UART. -Enter a series of octal halfwords +To use, enter a series of octal halfwords over UART then press G to jump to the beginning of SRAM and begin executing them as instructions. - This is the first step in bootstrapping the whole system. -## Better editor +## Hexedit + +A more robust and user-friendly memory editor, +which uses hexadecimal instead of octal, +validates input characters, +and displays the address and contents +of the halfword currently being edited. -A more robust and user-friendly hex editor. +The machine code for this editor +can be keyed in using octedit +as a series of 16-bit octal halfwords. ## Assembler diff --git a/hexedit/Makefile b/hexedit/Makefile new file mode 100644 index 0000000..4712bd1 --- /dev/null +++ b/hexedit/Makefile @@ -0,0 +1,21 @@ +all: build + +build: hexedit.uf2 + +hexedit.uf2: hexedit.elf + ../elf/elf2uf2 hexedit.elf hexedit.uf2 + +objects = hexedit.o main.o + +hexedit.elf: $(objects) + arm-none-eabi-ld -T pico_ram_only.ld -o hexedit.elf $(objects) ../setup/setup.so + +$(objects): %.o: %.s + arm-none-eabi-as -o $@ $< + +clean: + rm hexedit.elf hexedit.uf2 *.o + +flash: hexedit.uf2 + [ -h /dev/disk/by-label/RPI-RP2 ] || sleep 2s + cat hexedit.uf2 > /dev/disk/by-label/RPI-RP2 diff --git a/hexedit/hexedit.s b/hexedit/hexedit.s new file mode 100644 index 0000000..fb42d91 --- /dev/null +++ b/hexedit/hexedit.s @@ -0,0 +1,122 @@ +.syntax unified +.cpu cortex-m0plus +.thumb + +.type SETUP, %function +.global SETUP + +.type UARTTX, %function +.type UARTRX, %function +.type SENDHEX, %function + +.align 4 + +SETUP: LDR R0, [PC, #16] // 000000 044004 UARTRX + LDR R1, [PC, #20] // 000002 044405 UARTTX + LDR R2, [PC, #20] // 000004 045005 SENDHEX + MOV R9, R0 // 000006 043201 + MOV R10, R1 // 000010 043212 + MOV R11, R2 // 000012 043223 + LDR R7, [PC, #4] // 000014 047401 START ADDRESS + ADDS R6, R7, 1 // 000016 016176 + B MAINLOOP // 000020 160010 + .HWORD 0x0000 // 000022 000000 + .WORD UARTRX // 000024 010243 0x200010A3 + // 000026 040000 + .WORD UARTTX // 000030 010225 0x20001095 + // 000032 040000 + .WORD SENDHEX // 000034 010264 0x200010B5 + // 000036 040000 + .WORD 0x20001000 // 000040 010000 START ADDRESS + // 000042 020000 +MAINLOOP: MOVS R0, R7 // 000044 000070 PROMPT + BLX R11 // 000046 043730 SENDHEX + MOVS R0, 0x20 // 000050 020040 SPACE + BLX R10 // 000052 043720 UARTTX + LDRH R0, [R7] // 000054 104070 + BLX R11 // 000056 043730 SENDHEX + MOVS R0, 0x0D // 000060 020015 CARRIAGE RETURN + BLX R10 // 000062 043720 UARTTX + MOVS R0, R7 // 000064 000070 + BLX R11 // 000066 043730 SENDHEX + MOVS R0, 0x20 // 000070 020040 SPACE + BLX R10 // 000072 043720 UARTTX +10: BLX R9 // 000074 043710 COMMAND LOOP, UARTRX + CMP R0, 0x47 // 000076 024107 ASCII G + BNE 20f // 000100 150400 + BX R6 // 000102 043460 +20: CMP R0, 0x0D // 000104 024015 CARRIAGE RETURN + BNE 30f // 000106 150401 + ADDS R7, 0x2 // 000110 033402 + B MAINLOOP // 000112 163753 +30: CMP R0, 0x30 // 000114 024060 ASCII 0 + BNE MAINLOOP // 000116 150751 + BLX R10 // 000120 043720 UARTTX +40: BLX R9 // 000122 043710 UARTRX + CMP R0, 0x78 // 000124 024170 ASCII x + BNE 40b // 000126 150774 + BLX R10 // 000130 043720 UARTTX + MOVS R4, 0 // 000132 022000 + MOVS R5, 4 // 000134 022404 +50: BLX R9 // 000136 043710 HEX LOOP, UARTRX + CMP R0, 0x30 // 000140 024060 ASCII 0 + BLO 50b // 000142 151774 + CMP R0, 0x39 // 000144 024071 ASCII 9 + BLS 60f // 000146 154406 + CMP R0, 0x41 // 000150 024101 ASCII A + BLO 50b // 000152 151770 + CMP R0, 0x46 // 000154 024106 ASCII F + BHI 50b // 000156 154366 + BLX R10 // 000160 043720 UARTTX + SUBS R0, 0x37 // 000162 034067 ASCII A MINUS 10 + B 70f // 000164 160001 +60: BLX R10 // 000166 043720 UARTTX + SUBS R0, 0x30 // 000170 034060 ASCII 0 +70: LSLS R4, 4 // 000172 000444 + ADDS R4, R0 // 000174 014044 + SUBS R5, 1 // 000176 036401 + BNE 50b // 000200 150755 +80: BLX R9 // 000202 043710 UARTRX + CMP R0, 0x0D // 000204 024015 CARRIAGE RETURN + BNE 80b // 000206 150774 + BLX R10 // 000210 043720 UARTTX + STRH R4, [R7] // 000212 100074 + ADDS R7, 0x2 // 000214 033402 + MOVS R0, 0x0A // 000216 020012 NEW LINE + BLX R10 // 000220 043720 UARTTX + B MAINLOOP // 000222 163707 +UARTTX: LDR R1, [PC, #24] // 000224 044406 UART0_BASE + MOVS R3, 0x20 // 000226 021440 TX FIFO FULL +1: LDR R2, [R1, 0x18]// 000230 067012 UARTFR_OFST + TST R2, R3 // 000232 041032 + BNE 1b // 000234 150774 + STRB R0, [R1] // 000236 070010 UARTDR_OFST + BX LR // 000240 043560 +UARTRX: LDR R1, [PC, #12] // 000242 044403 + MOVS R3, 0x10 // 000244 021420 RX FIFO EMPTY +1: LDR R2, [R1, 0x18]// 000246 067012 UARTFR_OFST + TST R2, R3 // 000250 041032 + BNE 1b // 000252 150774 + LDRB R0, [R1] // 000254 074010 UARTDR_OFST + BX LR // 000256 043560 + .WORD 0x40034000 // 000260 040000 + // 000262 040003 +SENDHEX: PUSH {LR} // 000264 132400 + LSLS R4, R0, 0x10 // 000266 002004 16 BITS + MOVS R0, 0x30 // 000270 020060 ASCII 0 + BLX R10 // 000272 043720 UARTTX + MOVS R0, 0x78 // 000274 020170 ASCII x + BLX R10 // 000276 043720 + MOVS R5, 0x4 // 000300 022404 +0: MOVS R0, 0x1C // 000302 020034 + RORS R4, R0 // 000304 040704 + UXTB R0, R4 // 000306 131340 + CMP R0, 0x9 // 000310 024011 + BHI 1f // 000312 154001 + ADDS R0, 0x30 // 000314 030060 ASCII 0 + B 2f // 000316 160000 +1: ADDS R0, 0x37 // 000320 030067 ASCII A MINUS 10 +2: BLX R10 // 000322 043720 UARTTX + SUBS R5, 1 // 000324 036401 + BNE 0b // 000326 150764 + POP {PC} // 000330 136400 diff --git a/hexedit/main.s b/hexedit/main.s new file mode 100644 index 0000000..0b49339 --- /dev/null +++ b/hexedit/main.s @@ -0,0 +1,13 @@ +.syntax unified +.cpu cortex-m0plus +.thumb + +.type main, %function +.global main + +main: + bl start_xosc + bl setup_clocks + bl setup_gpio + bl setup_uart + b SETUP diff --git a/hexedit/pico_ram_only.ld b/hexedit/pico_ram_only.ld new file mode 100644 index 0000000..1185af5 --- /dev/null +++ b/hexedit/pico_ram_only.ld @@ -0,0 +1,14 @@ +ENTRY(main) + +MEMORY { + FLASH(rx) : ORIGIN = 0x10000000, LENGTH = 2M + SRAM(rwx) : ORIGIN = 0x20000000, LENGTH = 264K +} + +SECTIONS { + .text : { + main.o(.text); + *(.text); + . = ALIGN(4); + } > SRAM +} |