arm: Fix bug when calculating 24bit branch offsets, and add a test for
it.
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@ -295,7 +295,7 @@ impl ArmInstruction {
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}
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pub fn branch_offset(&self) -> i32 {
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((self.raw.bit_range(0..24) << 2) as i32) + 8
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(((self.raw.bit_range(0..24) << 8) as i32) >> 6).wrapping_add(8)
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}
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pub fn load_flag(&self) -> bool {
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@ -437,10 +437,28 @@ mod tests {
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use super::*;
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#[test]
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fn test_swi() {
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fn test_decode_swi() {
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// swi #0x1337
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let decoded = ArmInstruction::try_from(0xef001337).unwrap();
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assert_eq!(decoded.fmt, ArmInstructionFormat::SWI);
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assert_eq!(decoded.swi_comment(), 0x1337);
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}
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#[test]
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fn test_decode_branch_forwards() {
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// 0x20: b 0x30
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let decoded = ArmInstruction::try_from((0xea_00_00_02, 0x20)).unwrap();
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assert_eq!(decoded.fmt, ArmInstructionFormat::B_BL);
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assert_eq!(decoded.link_flag(), false);
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assert_eq!((decoded.pc as i32).wrapping_add(decoded.branch_offset()), 0x30);
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}
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#[test]
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fn test_decode_branch_backwards() {
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// 0x20: bl 0x10
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let decoded = ArmInstruction::try_from((0xeb_ff_ff_fa, 0x20)).unwrap();
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assert_eq!(decoded.fmt, ArmInstructionFormat::B_BL);
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assert_eq!(decoded.link_flag(), true);
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assert_eq!((decoded.pc as i32).wrapping_add(decoded.branch_offset()), 0x10);
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}
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}
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