Experimental support for storing const strings in SPI flash or IRAM
As discussed in #11 Known limitations: - Only supports l8ui/l16ui - Unoptimised load routine - Not called from DoubleExceptionHandler but should be - Doesn't restore state properly when falling through to fatal exception handler
This commit is contained in:
Angus Gratton
parent
25e124a612
commit
bfd38cd1e2
3 changed files with 247 additions and 0 deletions
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@ -173,12 +173,14 @@ CallNMIExceptionHandler:
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/* Some UserException causes, see table Table 4–64 in ISA reference */
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#define CAUSE_SYSCALL 1
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#define CAUSE_LOADSTORE 3
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#define CAUSE_LVL1INT 4
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.type CallUserExceptionHandler, @function
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CallUserExceptionHandler:
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rsr.exccause a0
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beqi a0, CAUSE_SYSCALL, UserSyscallHandler
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beqi a0, CAUSE_LOADSTORE, UserLoadStoreExceptionHandler
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mov a0, sp
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addi sp, sp, -0x50
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s32i a0, sp, 0x10
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@ -242,6 +244,132 @@ UserSyscallHandler:
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rsr.excsave1 a0
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rfe
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.section .bss
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.global LoadStoreErrorFlag
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.align 4
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LoadStoreErrorFlag:
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.long 0
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.long 0
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.long 0
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.long 0
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.section .data
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.align 4
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PRINT_ADDR:
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.string "0x%08lx '%c'\r\n"
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PRINT_MULTI:
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.string "a3=0x%08lx a4=0x%08lx a5=0x%08lx a6=0x%08lx a7=0x%08lx\r\n"
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.text
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.section .vecbase.text
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.literal_position
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.align 4
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.global UserLoadStoreExceptionHandler
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/* "Fix" LoadStoreException exceptions thatare l8/l16 from an Instruction region */
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UserLoadStoreExceptionHandler:
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addi sp, sp, -0x40
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s32i a2, sp, 0x08
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rsr.excsave1 a2 /* a0 value */
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s32i a2, sp, 0x00
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addi a2, sp, 0x40
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s32i a2, sp, 0x04 /* original sp value */
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s32i a3, sp, 0x0c
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s32i a4, sp, 0x10
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s32i a5, sp, 0x14
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s32i a6, sp, 0x18
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s32i a7, sp, 0x1c
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s32i a8, sp, 0x20
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s32i a9, sp, 0x24
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s32i a10, sp, 0x28
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s32i a11, sp, 0x2c
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s32i a12, sp, 0x30
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s32i a13, sp, 0x34
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s32i a14, sp, 0x38
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s32i a15, sp, 0x3c
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/* Check the top nibble of the faulting address is 4, otherwise
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we can't help out here */
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rsr.excvaddr a2
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extui a2, a2, 28, 4
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bnei a2, 0x4, .Lcant_fix
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/* Load the instruction we failed to execute */
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rsr.epc1 a3
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movi a4, ~3
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and a2, a3, a4
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l32i a4, a2, 0
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l32i a5, a2, 4
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ssa8l a3
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src a4, a5, a4
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/* a4 is now the instruction that failed */
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/* example l8ui instr 040c72 */
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movi a2, 0x00F00F /* l8ui/l16ui opcode mask */
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and a3, a4, a2
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movi a8, 0xFF
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movi a5, 0x000002 /* l8ui opcode after masking */
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beq a3, a5, .Lcan_fix
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movi a8, 0xFFFF
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movi a5, 0x001002 /* l16ui opcode after masking */
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beq a3, a5, .Lcan_fix
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.Lcant_fix:
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/* not an l8ui or an l16ui, or not in the instruction space, so bomb out
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TODO: the exception dump will have some wrong values in it */
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movi a2, PRINT_ADDR
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movi a3, 0xafafafaf
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call0 printf
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call0 sdk_user_fatal_exception_handler
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.Lcan_fix:
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/* verified an 8- or 16-bit read in an instruction address space.
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a4 holds instruction, a8 holds mask
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*/
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extui a2, a4, 4, 4 /* a2 is destination register 0-15 */
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slli a2, a2, 2 /* a2 is now offset of destination register, relative to stack pointer */
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rsr.sar a6
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rsr.excvaddr a3
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ssa8l a3 /* sar is the shift to extract a3's byte */
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movi a4, ~3
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and a4, a3, a4 /* a4 is word aligned read address */
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l32i a5, a4, 0 /* perform the actual read */
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srl a5, a5
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and a5, a5, a8 /* mask off bits we need for an l8/l16 */
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wsr.sar a6
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add a6, sp, a2
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s32i a5, a6, 0 /* overwrite correct value on register slot @ stack+a2 */
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/* Footer*/
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//Increment PC
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rsr.epc1 a2
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addi a3, a2, 0x3
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wsr.epc1 a3
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// Restore registers
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l32i a0, sp, 0x00
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l32i a2, sp, 0x08
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l32i a3, sp, 0x0c
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l32i a4, sp, 0x10
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l32i a5, sp, 0x14
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l32i a6, sp, 0x18
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l32i a7, sp, 0x1c
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l32i a8, sp, 0x20
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l32i a9, sp, 0x24
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l32i a10, sp, 0x28
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l32i a11, sp, 0x2c
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l32i a12, sp, 0x30
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l32i a13, sp, 0x34
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l32i a14, sp, 0x38
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l32i a15, sp, 0x3c
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l32i sp, sp, 0x04
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rfe
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.global _xt_user_exit
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.type _xt_user_exit, @function
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_xt_user_exit:
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2
examples/experiments/unaligned_load/Makefile
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2
examples/experiments/unaligned_load/Makefile
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@ -0,0 +1,2 @@
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PROGRAM=unaligned_load
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include ../../../common.mk
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117
examples/experiments/unaligned_load/unaligned_load.c
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117
examples/experiments/unaligned_load/unaligned_load.c
Normal file
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@ -0,0 +1,117 @@
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/* Very basic example that just demonstrates we can run at all!
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*/
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#include "esp/rom.h"
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#include "espressif/esp_common.h"
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#include "espressif/sdk_private.h"
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#include "FreeRTOS.h"
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#include "task.h"
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#include "queue.h"
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#include "string.h"
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#include "strings.h"
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#define TESTSTRING "O hai there! %d %d %d"
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const char *dramtest = TESTSTRING;
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const __attribute__((section(".iram1.notrodata"))) char iramtest[] = TESTSTRING;
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const __attribute__((section(".text.notrodata"))) char iromtest[] = TESTSTRING;
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INLINED uint32_t get_ccount (void)
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{
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uint32_t ccount;
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asm volatile ("rsr.ccount %0" : "=a" (ccount));
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return ccount;
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}
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typedef void (* test_with_fn_t)(const char *string);
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char buf[64];
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void test_memcpy_aligned(const char *string)
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{
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memcpy(buf, string, 16);
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}
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void test_memcpy_unaligned(const char *string)
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{
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memcpy(buf, string, 15);
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}
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void test_memcpy_unaligned2(const char *string)
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{
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memcpy(buf, string+1, 15);
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}
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void test_strcpy(const char *string)
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{
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strcpy(buf, string);
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}
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void test_sprintf(const char *string)
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{
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sprintf(buf, string, 1, 2, 3);
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}
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void test_sprintf_arg(const char *string)
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{
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sprintf(buf, "%s", string);
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}
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void test_naive_strcpy(const char *string)
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{
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char *to = buf;
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while((*to++ = *string++))
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;
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}
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#define TEST_REPEATS 1000
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void test_noop(const char *string)
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{
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}
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uint32_t IRAM run_test(const char *string, test_with_fn_t testfn, const char *testfn_label, uint32_t nullvalue, bool evict_cache)
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{
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printf(" .. against %30s: ", testfn_label);
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vPortEnterCritical();
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uint32_t before = get_ccount();
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for(int i = 0; i < TEST_REPEATS; i++) {
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testfn(string);
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if(evict_cache) {
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Cache_Read_Disable();
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Cache_Read_Enable(0,0,1);
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}
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}
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uint32_t after = get_ccount();
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vPortExitCritical();
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uint32_t instructions = (after-before)/TEST_REPEATS - nullvalue;
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printf("%5ld instructions\r\n", instructions);
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return instructions;
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}
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void test_string(const char *string, char *label, bool evict_cache)
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{
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printf("Testing %s (%p) '%s'\r\n", label, string, string);
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printf("Formats as: '");
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printf(string, 1, 2, 3);
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printf("'\r\n");
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uint32_t nullvalue = run_test(string, test_noop, "null op", 0, evict_cache);
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run_test(string, test_memcpy_aligned, "memcpy - aligned len", nullvalue, evict_cache);
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run_test(string, test_memcpy_unaligned, "memcpy - unaligned len", nullvalue, evict_cache);
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run_test(string, test_memcpy_unaligned2, "memcpy - unaligned start&len", nullvalue, evict_cache);
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run_test(string, test_strcpy, "strcpy", nullvalue, evict_cache);
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run_test(string, test_naive_strcpy, "naive strcpy", nullvalue, evict_cache);
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run_test(string, test_sprintf, "sprintf", nullvalue, evict_cache);
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run_test(string, test_sprintf_arg, "sprintf format arg", nullvalue, evict_cache);
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}
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void user_init(void)
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{
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sdk_uart_div_modify(0, UART_CLK_FREQ / 115200);
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printf("\r\n\r\nSDK version:%s\r\n", sdk_system_get_sdk_version());
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test_string(dramtest, "DRAM", 0);
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test_string(iramtest, "IRAM", 0);
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test_string(iromtest, "Cached flash", 0);
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test_string(iromtest, "'Uncached' flash", 1);
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}
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